Science.gov

Sample records for katrinas wind fields

  1. Hurricane Katrina Wind Investigation Report

    SciTech Connect

    Desjarlais, A. O.

    2007-08-15

    This investigation of roof damage caused by Hurricane Katrina is a joint effort of the Roofing Industry Committee on Weather Issues, Inc. (RICOWI) and the Oak Ridge National Laboratory/U.S. Department of Energy (ORNL/DOE). The Wind Investigation Program (WIP) was initiated in 1996. Hurricane damage that met the criteria of a major windstorm event did not materialize until Hurricanes Charley and Ivan occurred in August 2004. Hurricane Katrina presented a third opportunity for a wind damage investigation in August 29, 2005. The major objectives of the WIP are as follows: (1) to investigate the field performance of roofing assemblies after major wind events; (2) to factually describe roofing assembly performance and modes of failure; and (3) to formally report results of the investigations and damage modes for substantial wind speeds The goal of the WIP is to perform unbiased, detailed investigations by credible personnel from the roofing industry, the insurance industry, and academia. Data from these investigations will, it is hoped, lead to overall improvement in roofing products, systems, roofing application, and durability and a reduction in losses, which may lead to lower overall costs to the public. This report documents the results of an extensive and well-planned investigative effort. The following program changes were implemented as a result of the lessons learned during the Hurricane Charley and Ivan investigations: (1) A logistics team was deployed to damage areas immediately following landfall; (2) Aerial surveillance--imperative to target wind damage areas--was conducted; (3) Investigation teams were in place within 8 days; (4) Teams collected more detailed data; and (5) Teams took improved photographs and completed more detailed photo logs. Participating associations reviewed the results and lessons learned from the previous investigations and many have taken the following actions: (1) Moved forward with recommendations for new installation procedures

  2. Gone with the Wind? Integrity and Hurricane Katrina

    ERIC Educational Resources Information Center

    Lucas, Frances; Katz, Brit

    2011-01-01

    Hurricane Katrina slammed into 80 miles of Mississippi shoreline on August 29, 2005. It was the nation's worst natural disaster, a perfect storm. One hundred sixty miles-per-hour winds sent 55-foot-tall waves and a 30-foot wall of water across the shore and miles inland. It displaced 400,000 residents along the coast of the Mississippi, and…

  3. Evaluation of Vertically Resolved Water Winds from AIRS using Hurricane Katrina

    NASA Technical Reports Server (NTRS)

    Aumann, Hartmut H.; Dobkowski, Edwin C.; Gregorich, David T.

    2005-01-01

    The knowledge of wind velocity as a function of altitude is key to weather forecast improvements. The ability of hyperspectral sounders in principle to measure vertically resolved water winds, which has long been recognized, has been tested with Atmospheric Infrared Sounder (AIRS) data. AIRS retrievals of total column water above 300 mb have been correlated with the radiosonde upper-tropospheric wind velocity and moisture data. The excellent correlation is illustrated with results obtained from hurricane Katrina and from the western United States. AIRS is a hyperspectral infrared sounder in low Earth orbit. It was launched in May 2002. We illustrate the use of AIRS data for the measurement of upper tropospheric water by using the 2387/cm CO2 R-branch channel and the 1551/cm water vapor channel. The 2387/cm channel measures the temperature at 300 mb totally independent of water vapor. The weighting function of the 1551/cm channel peaks at 300 mb only under moist conditions; the peak shifts downward (higher temperature) for less water and upward (lower temperature) for more water. The difference between the brightness temperatures bt2387 and bt1551 cancels the local several degree weather related variability of the temperature and measures the component due to the water vapor at 300 mb.

  4. Hurricane Katrina

    Atmospheric Science Data Center

    2014-05-15

    article title:  Flooding in the Aftermath of Hurricane Katrina   ... River that was not apparent before Katrina. The post-Katrina flooding along the edges of Lake Pontchartrain and the city of New Orleans is ...

  5. Surviving Hurricane Katrina: Winds of Change Transform a New Orleans Addiction Treatment Agency

    ERIC Educational Resources Information Center

    Toriello, Paul J.; Pedersen-Wasson, Else; Crisham, Erin M.; Ellis, Robert; Morse, Patricia; Morse, Edward V.

    2007-01-01

    Hurricane Katrina's impact on the operations of the largest residential, addiction treatment organization in New Orleans is described. Pre- and post-Katrina experiences are discussed and augmented with organizational performance data. Suggestions for future research are provided. (Contains 4 figures.)

  6. Solar Wind Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Smith, E. J.

    1995-01-01

    The magnetic fields originate as coronal fields that are converted into space by the supersonic, infinitely conducting, solar wind. On average, the sun's rotation causes the field to wind up and form an Archimedes Spiral. However, the field direction changes almost continuously on a variety of scales and the irregular nature of these changes is often interpreted as evidence that the solar wind flow is turbulent.

  7. Modeling Hurricane Katrina's merchantable timber and wood damage in south Mississippi using remotely sensed and field-measured data

    NASA Astrophysics Data System (ADS)

    Collins, Curtis Andrew

    Ordinary and weighted least squares multiple linear regression techniques were used to derive 720 models predicting Katrina-induced storm damage in cubic foot volume (outside bark) and green weight tons (outside bark). The large number of models was dictated by the use of three damage classes, three product types, and four forest type model strata. These 36 models were then fit and reported across 10 variable sets and variable set combinations for volume and ton units. Along with large model counts, potential independent variables were created using power transforms and interactions. The basis of these variables was field measured plot data, satellite (Landsat TM and ETM+) imagery, and NOAA HWIND wind data variable types. As part of the modeling process, lone variable types as well as two-type and three-type combinations were examined. By deriving models with these varying inputs, model utility is flexible as all independent variable data are not needed in future applications. The large number of potential variables led to the use of forward, sequential, and exhaustive independent variable selection techniques. After variable selection, weighted least squares techniques were often employed using weights of one over the square root of the pre-storm volume or weight of interest. This was generally successful in improving residual variance homogeneity. Finished model fits, as represented by coefficient of determination (R2), surpassed 0.5 in numerous models with values over 0.6 noted in a few cases. Given these models, an analyst is provided with a toolset to aid in risk assessment and disaster recovery should Katrina-like weather events reoccur.

  8. Project Katrina

    ERIC Educational Resources Information Center

    Aghayan, Carol; Schellhaas, Andree; Wayne, Angela; Burts, Diane C.; Buchanan, Teresa K.; Benedict, Joan

    2005-01-01

    This article describes a spontaneous project that emerged from a group of 3- and 4-year-old children in Louisiana after Hurricane Katrina. The article describes how the teachers adapted the classroom and curriculum to meet the diverse needs of children who were evacuees, as well as those children who were affected in other ways by the…

  9. Time dependent wind fields

    NASA Technical Reports Server (NTRS)

    Chelton, D. B.

    1986-01-01

    Two tasks were performed: (1) determination of the accuracy of Seasat scatterometer, altimeter, and scanning multichannel microwave radiometer measurements of wind speed; and (2) application of Seasat altimeter measurements of sea level to study the spatial and temporal variability of geostrophic flow in the Antarctic Circumpolar Current. The results of the first task have identified systematic errors in wind speeds estimated by all three satellite sensors. However, in all cases the errors are correctable and corrected wind speeds agree between the three sensors to better than 1 ms sup -1 in 96-day 2 deg. latitude by 6 deg. longitude averages. The second task has resulted in development of a new technique for using altimeter sea level measurements to study the temporal variability of large scale sea level variations. Application of the technique to the Antarctic Circumpolar Current yielded new information about the ocean circulation in this region of the ocean that is poorly sampled by conventional ship-based measurements.

  10. Children’s Mental Health Care following Hurricane Katrina: A Field Trial of Trauma-Focused Psychotherapies

    PubMed Central

    Jaycox, Lisa H.; Cohen, Judith A.; Mannarino, Anthony P.; Walker, Douglas W.; Langley, Audra K.; Gegenheimer, Kate L.; Scott, Molly; Schonlau, Matthias

    2010-01-01

    New Orleans school children participated in an assessment and field trial of two interventions 15 months after Hurricane Katrina. Children (N = 195) reported on hurricane exposure, lifetime trauma exposure, peer and parent support, posttraumatic stress disorder (PTSD), and depressive symptoms. Teachers reported on behavior. At baseline, 60.5% screened positive for PTSD symptoms and were offered a group intervention at school or individual treatment at a mental health clinic. Uptake of the mental health care was uneven across intervention groups, with 98% beginning the school intervention, compared to 37% beginning at the clinic. Both treatments led to significant symptom reduction of PTSD symptoms but many still had elevated PTSD symptoms at post treatment. Implications for future postdisaster mental health work are discussed. PMID:20419730

  11. Comparison of field and wind tunnel Darrieus wind turbine data

    SciTech Connect

    Sheldahl, R.E.

    1981-01-01

    A 2-m-dia Darrieus Vertical Axis Wind Turbine with NACA-0012 blades was extensively tested in the Vought Corporation Low Speed Wind Tunnel. This same turbine was installed in the field at the Sandia National Laboratories Wind Turbine Test Site and operated to determine if field data corresponded to data obtained in the wind tunnel. It is believed that the accuracy of the wind tunnel test data was verified and thus the credibility of that data base was further established.

  12. Dynamical downscaling of wind fields for wind power applications

    NASA Astrophysics Data System (ADS)

    Mengelkamp, H.-T.; Huneke, S.; Geyer, J.

    2010-09-01

    Dynamical downscaling of wind fields for wind power applications H.-T. Mengelkamp*,**, S. Huneke**, J, Geyer** *GKSS Research Center Geesthacht GmbH **anemos Gesellschaft für Umweltmeteorologie mbH Investments in wind power require information on the long-term mean wind potential and its temporal variations on daily to annual and decadal time scales. This information is rarely available at specific wind farm sites. Short-term on-site measurements usually are only performed over a 12 months period. These data have to be set into the long-term perspective through correlation to long-term consistent wind data sets. Preliminary wind information is often asked for to select favourable wind sites over regional and country wide scales. Lack of high-quality wind measurements at weather stations was the motivation to start high resolution wind field simulations The simulations are basically a refinement of global scale reanalysis data by means of high resolution simulations with an atmospheric mesoscale model using high-resolution terrain and land-use data. The 3-dimensional representation of the atmospheric state available every six hours at 2.5 degree resolution over the globe, known as NCAR/NCEP reanalysis data, forms the boundary conditions for continuous simulations with the non-hydrostatic atmospheric mesoscale model MM5. MM5 is nested in itself down to a horizontal resolution of 5 x 5 km². The simulation is performed for different European countries and covers the period 2000 to present and is continuously updated. Model variables are stored every 10 minutes for various heights. We have analysed the wind field primarily. The wind data set is consistent in space and time and provides information on the regional distribution of the long-term mean wind potential, the temporal variability of the wind potential, the vertical variation of the wind potential, and the temperature, and pressure distribution (air density). In the context of wind power these data are used

  13. Response of dominant wind wave fields to abrupt wind increase

    NASA Astrophysics Data System (ADS)

    Caulliez, Guillemette

    2013-04-01

    Over the last decades, significant progress has been made in modelling wave field development by wind observed at sea, based on more elaborated numerical schemes and refined parametrizations of wind energy input and wave dissipation. In such models, the wind wave growth in space or time is generally governed by the average wind speed evaluated at one reference level and the natural wind speed variability is neglected. However, the impact of this assumption is not really known, mainly because of the lack of appropriate observations. To revisit this question, we report a detailed laboratory investigation aimed at describing the dominant wave field evolution resulting from an abrupt local wind speed increase. The experiments were conducted in the large Marseille-Luminy wind wave tank for moderate to high wind conditions. At 23 m fetch, a contraction of the wind tunnel section by a convergent profile created a spatial wind speed acceleration over a distance of about 2 m. Downwind, the wind speed, enhanced by a factor 1.4, was kept constant up to the end of the water tank. The wind wave field development induced by such a "wind gust" was investigated at successive fetches by wave probes and compared to those observed at similar fetches for homogeneous wind conditions. When wind increases, these observations first revealed no dramatic change in the evolution of the dominant spectral peak with fetch. The dominant wave energy which increases slowly for constant wind conditions, follows the wind speed but with a significant space lag. For well-established gravity wave fields, the space relaxation scales which describe this evolution do not depend noticeably on wind, all the curves collapse into a single one when wave quantities are normalized by their value observed just upstream the convergent profile. The wave growth rate observed for the new equilibrium state can be described by the Hasselman et al. (1973) relationship but with an "equivalent'' shorter fetch since, in

  14. Wind Turbines Adaptation to the Variability of the Wind Field

    NASA Astrophysics Data System (ADS)

    Ulianov, Yuriy; Martynenko, Gennadii; Misaylov, Vitaliy; Soliannikova, Iuliia

    2010-05-01

    WIND TURBINES ADAPTATION TO THE VARIABILITY OF THE WIND FIELD The subject of our scientific research is wind power turbines (WPT) with the horizontal axis which were now common in the world. Efficient wind turbines work is largely determined by non-stationarity of the wind field, expressed in its gustiness, the presence of vertical and horizontal shifts of wind speed and direction. At critical values of the wind parameters WPT has aerodynamic and mechanical overload, leading to breakdowns, premature wear and reduce the life of the wind turbine. To prevent accidents at the peak values of wind speed it is used the regulatory system of windwheels. WPT control systems provide a process orientation of the wind turbine rotor axis in the line of the mean wind. Wind turbines are also equipped with braking device used to protect against breakdowns when a significant increase in the wind. In general, all these methods of regulation are not always effective. Thus, in practice there may be situations when the wind speed is many times greater than the stated limit. For example, if there are microbursts in the atmospheric boundary layer, low-level wind shears caused by its gust front, storms, etc. It is required for a wind power turbine adaptation to intensive short-term wind impulses and considerable vertical wind shifts that the data about them shall be obtained ahead of time. To do this it is necessary to have the information on the real structure of the wind field in the area of the blade sweep for the minimum range against the wind that is determined by the mean speed and the system action time. The implementation of acoustic and laser traditional wind sounding systems is limited by ambient acoustic noise, by heavy rain, snowfall and by fog. There are free of these disadvantages the inclined radioacoustic sounding (IRASS) technique which works for a system of remote detection and control of wind gusts. IRASS technique is realized as low-potential Doppler pulse radar

  15. LIDAR Wind Speed Measurements of Evolving Wind Fields

    SciTech Connect

    Simley, E.; Pao, L. Y.

    2012-07-01

    Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements are also evaluated with a large eddy simulation of a stable boundary layer provided by the National Center for Atmospheric Research. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios.

  16. Wide Area Wind Field Monitoring Status & Results

    SciTech Connect

    Alan Marchant; Jed Simmons

    2011-09-30

    Volume-scanning elastic has been investigated as a means to derive 3D dynamic wind fields for characterization and monitoring of wind energy sites. An eye-safe volume-scanning lidar system was adapted for volume imaging of aerosol concentrations out to a range of 300m. Reformatting of the lidar data as dynamic volume images was successfully demonstrated. A practical method for deriving 3D wind fields from dynamic volume imagery was identified and demonstrated. However, the natural phenomenology was found to provide insufficient aerosol features for reliable wind sensing. The results of this study may be applicable to wind field measurement using injected aerosol tracers.

  17. Field verification of the wind tunnel coefficients

    NASA Technical Reports Server (NTRS)

    Gawronski, W. K.; Mellstrom, J. A.

    1994-01-01

    Accurate information about wind action on antennas is required for reliable prediction of antenna pointing errors in windy weather and for the design of an antenna controller with wind disturbance rejection properties. The wind tunnel data obtained 3 years ago using a scaled antenna model serves as an antenna industry standard, frequently used for the first purpose. The accuracy of the wind tunnel data has often been challenged, since they have not yet been tested in a field environment (full-aized antenna, real wind, actual terrain, etc.). The purpose of this investigation was to obtain selected field measurements and compare them with the available wind tunnel data. For this purpose, wind steady-state torques of the DSS-13 antenna were measured, and dimensionless wind torque coefficients were obtained for a variety of yaw and elevation angles. The results showed that the differences between the wind tunnel torque coefficients and the field torque coefficients were less than 10 percent of their values. The wind-gusting action on the antenna was characterized by the power spectra of the antenna encoder and the antenna torques. The spectra showed that wind gusting primarily affects the antenna principal modes.

  18. LIDAR Wind Speed Measurements of Evolving Wind Fields

    SciTech Connect

    Simley, E.; Pao, L. Y.; Kelley, N.; Jonkman, B.; Frehlich, R.

    2012-01-01

    Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems that are designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed the validity of physicist G.I. Taylor's 1938 frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations using the National Renewable Energy Laboratory's (NREL's) 5-megawatt turbine model to create a more realistic measurement model. A simple model of wind evolution was applied to a frozen wind field that was used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements were also evaluated using a large eddy simulation (LES) of a stable boundary layer that was provided by the National Center for Atmospheric Research. The LIDAR measurement scenario investigated consists of a hub-mounted LIDAR that scans a circle of points upwind of the turbine in order to estimate the wind speed component in the mean wind direction. Different combinations of the preview distance that is located upwind of the rotor and the radius of the scan circle were analyzed. It was found that the dominant source of measurement error for short preview distances is the detection of transverse and vertical wind speeds from the line-of-sight LIDAR measurement. It was discovered in previous studies that, in the absence of wind evolution, the dominant source of error for large preview distances

  19. Recovering from Hurricane Katrina

    ERIC Educational Resources Information Center

    Coleman, Nadine

    2006-01-01

    The Gulf Coast region suffered an unusually severe hurricane season in 2005: Hurricane Katrina (August 28-29, 2005) devastated much of southern Mississippi and Louisiana. Approximately 2,700 licensed early care and education facilities in those states and in Alabama were affected by Katrina, in addition to an unknown number of family child care…

  20. Erosion by Wind: Field Measurement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion and deposition results when wind moves soil from a bare susceptible surface to another location downwind. Although placement of permanent vertical references such as pins or rods has been used to measure soil redistribution, it is more commonly measured by capturing sediment moving dur...

  1. Ocean Wave Simulation Based on Wind Field.

    PubMed

    Li, Zhongyi; Wang, Hao

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates. PMID:26808718

  2. Ocean Wave Simulation Based on Wind Field

    PubMed Central

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates. PMID:26808718

  3. Wavelet analysis for wind fields estimation.

    PubMed

    Leite, Gladeston C; Ushizima, Daniela M; Medeiros, Fátima N S; de Lima, Gilson G

    2010-01-01

    Wind field analysis from synthetic aperture radar images allows the estimation of wind direction and speed based on image descriptors. In this paper, we propose a framework to automate wind direction retrieval based on wavelet decomposition associated with spectral processing. We extend existing undecimated wavelet transform approaches, by including à trous with B(3) spline scaling function, in addition to other wavelet bases as Gabor and Mexican-hat. The purpose is to extract more reliable directional information, when wind speed values range from 5 to 10 ms(-1). Using C-band empirical models, associated with the estimated directional information, we calculate local wind speed values and compare our results with QuikSCAT scatterometer data. The proposed approach has potential application in the evaluation of oil spills and wind farms. PMID:22219699

  4. Wavelet Analysis for Wind Fields Estimation

    PubMed Central

    Leite, Gladeston C.; Ushizima, Daniela M.; Medeiros, Fátima N. S.; de Lima, Gilson G.

    2010-01-01

    Wind field analysis from synthetic aperture radar images allows the estimation of wind direction and speed based on image descriptors. In this paper, we propose a framework to automate wind direction retrieval based on wavelet decomposition associated with spectral processing. We extend existing undecimated wavelet transform approaches, by including à trous with B3 spline scaling function, in addition to other wavelet bases as Gabor and Mexican-hat. The purpose is to extract more reliable directional information, when wind speed values range from 5 to 10 ms−1. Using C-band empirical models, associated with the estimated directional information, we calculate local wind speed values and compare our results with QuikSCAT scatterometer data. The proposed approach has potential application in the evaluation of oil spills and wind farms. PMID:22219699

  5. Hurricane Katrina disaster diplomacy.

    PubMed

    Kelman, Ilan

    2007-09-01

    Hurricane Katrina struck the United States at the end of August 2005. The consequent devastation appeared to be beyond the US government's ability to cope with and aid was offered by several states in varying degrees of conflict with the US. Hurricane Katrina therefore became a potential case study for 'disaster diplomacy', which examines how disaster-related activities do and do not yield diplomatic gains. A review of past disaster diplomacy work is provided. The literature's case studies are then categorised using a new typology: propinquity, aid relationship, level and purpose. Hurricane Katrina and its aftermath are then placed in the context of the US government's foreign policy, the international response to the disaster and the US government's reaction to these responses. The evidence presented is used to discuss the potential implications of Hurricane Katrina disaster diplomacy, indicating that factors other than disaster-related activities generally dominate diplomatic relations and foreign policy. PMID:17714169

  6. Wind gust models derived from field data

    NASA Technical Reports Server (NTRS)

    Gawronski, W.

    1995-01-01

    Wind data measured during a field experiment were used to verify the analytical model of wind gusts. Good coincidence was observed; the only discrepancy occurred for the azimuth error in the front and back winds, where the simulated errors were smaller than the measured ones. This happened because of the assumption of the spatial coherence of the wind gust model, which generated a symmetric antenna load and, in consequence, a low azimuth servo error. This result indicates a need for upgrading the wind gust model to a spatially incoherent one that will reflect the real gusts in a more accurate manner. In order to design a controller with wind disturbance rejection properties, the wind disturbance should be known at the input to the antenna rate loop model. The second task, therefore, consists of developing a digital filter that simulates the wind gusts at the antenna rate input. This filter matches the spectrum of the measured servo errors. In this scenario, the wind gusts are generated by introducing white noise to the filter input.

  7. Near-ground tornado wind fields

    SciTech Connect

    McDonald, J.R.

    1984-07-01

    A study of near-ground tornado wind fields has been conducted by inspecting damage and debris patterns found in tornado damage paths. Because there were no significant tornado events (F4 or greater) during the contract performance period, data from the literature and the files of the Institute for Disaster Research were used to perform the analyses. The results indicate: (1) maximum tornado wind speed ever experienced or expected is in the range of 250 to 300 mph; (2) appearance of damage, taken by itself, is a misleading parameter of tornado intensity. Type of construction, age of construction, materials and other construction features significantly affect structural performance of a building subjected to wind loads and should be taken into account in assigning Fujita-Scale ratings; (3) damage to forests gives a good indication of tornado wind field flow patterns, but do not give verifiable values of wind speed; (4) factors such as translational speed, wind direction and path width affect appearance of damage or a tornado; and (5) even the most awesome appearing missiles do not require incredible wind speeds to explain them. Some progress in computer simulation of tornado missiles have been made. 31 references, 8 figures, 2 tables.

  8. Katrina Retrospective: 5 Years Later

    NASA Video Gallery

    Five years after Hurricane Katrina struck the Gulf Coast, NASA revisits the storm with a short video that shows Katrina as captured by satellites. Before and during the hurricane's landfall, NASA p...

  9. Coronal magnetic fields and the solar wind

    NASA Technical Reports Server (NTRS)

    Newkirk, G., Jr.

    1972-01-01

    Current information is presented on coronal magnetic fields as they bear on problems of the solar wind. Both steady state fields and coronal transient events are considered. A brief critique is given of the methods of calculating coronal magnetic fields including the potential (current free) models, exact solutions for the solar wind and field interaction, and source surface models. These solutions are compared with the meager quantitative observations which are available at this time. Qualitative comparisons between the shapes of calculated magnetic field lines and the forms visible in the solar corona at several recent eclipses are displayed. These suggest that: (1) coronal streamers develop above extended magnetic arcades which connect unipolar regions of opposite polarity; and (2) loops, arches, and rays in the corona correspond to preferentially filled magnetic tubes in the approximately potential field.

  10. The impact of Ensemble-based data assimilation on the predictability of landfalling Hurricane Katrina (2005)

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Pu, Z.

    2012-12-01

    Accurate forecasts of the track, intensity and structure of a landfalling hurricane can save lives and mitigate social impacts. Over the last two decades, significant improvements have been achieved for hurricane forecasts. However, only a few of studies have emphasized landfalling hurricanes. Specifically, there are difficulties in predicting hurricane landfall due to the uncertainties in representing the atmospheric near-surface conditions in numerical weather prediction models, the complicated interaction between the atmosphere and the ocean, and the multiple-scale dynamical and physical processes accompanying storm development. In this study, the impact of the assimilation of conventional and satellite observations on the predictability of landfalling hurricanes is examined by using a mesoscale community Weather Research and Forecasting (WRF) model and an ensemble Kalman filter developed by NCAR Data Assimilation Research Testbed (DART). Hurricane Katrina (2005) was chosen as a case study since it was one of the deadliest disasters in US history. The minimum sea level pressure from the best track, QuikScat ocean surface wind vectors, surface mesonet observations, airborne Doppler radar derived wind components and available conventional observations are assimilated in a series of experiments to examine the data impacts on the predictability of Hurricane Katrina. The analyses and forecasts show that ensemble-based data assimilation significantly improves the forecast of Hurricane Katrina. The assimilation improves the track forecast through modifying the storm structures and related environmental fields. Cyclonic increments are clearly seen in vorticity and wind analyses. Temperature and humidity fields are also modified by the data assimilation. The changes in relevant fields help organize the structure of the storm, intensify the circulation, and result in a positive impact on the evolution of the storm in both analyses and forecasts. The forecasts in the

  11. Providing continuity of care for chronic diseases in the aftermath of Katrina: from field experience to policy recommendations.

    PubMed

    Arrieta, Martha I; Foreman, Rachel D; Crook, Errol D; Icenogle, Marjorie L

    2009-10-01

    This study sought to elicit challenges and solutions in the provision of health care to those with chronic diseases after Hurricane Katrina in coastal Alabama and Mississippi. In-depth interviews with 30 health and social service providers (key informants) and 4 focus groups with patients with chronic diseases were conducted. Subsequently an advisory panel of key informants was convened. Findings were summarized and key informants submitted additional feedback. The chronic diseases identified as medical management priorities by key informants were mental health, diabetes mellitus, hypertension, respiratory illness, end-stage renal disease, cardiovascular disease, and cancer. The most frequently mentioned barrier to providing care was maintaining continuity of medications. Contributing factors were inadequate information (inaccessible medical records, poor patient knowledge) and financial constraints. Implemented or suggested solutions included relaxation of insurance limitations preventing advance prescription refills; better predisaster patient education to improve medical knowledge; promotion of personal health records; support for information technology systems at community health centers, in particular electronic medical records; improved allocation of donated medications/medical supplies (centralized coordination, decentralized distribution); and networking between local responders and external aid. PMID:19865042

  12. Satellite imagery maps Hurricane Katrina-induced flooding and oil slicks

    NASA Astrophysics Data System (ADS)

    Rykhus, Russell P.

    In the early morning of 29 August 2005, Hurricane Katrina made landfall near Buras, Louisiana, as a Category 4 hurricane. With wind speeds of about 233 kilometers per hour, a storm surge of 8.5 meters, and heavy rains, Katrina pounded the U.S. Gulf Coast states of Alabama, Louisiana, and Mississippi with lifethreatening flooding and destruction. Katrina's high winds and storm surge breached the levees protecting New Orleans, a city located below sea level, and flooded approximately 80% of the city.Katrina also caused major damage to the region's oil and natural gas production and refining capabilities. On 2 September 2005, the Associated Press reported that Katrina had damaged 58 oil platforms, 30 of which were reported lost; one damaged platform had been blown nearly 100 km from its original location.

  13. Solar wind interaction with lunar magnetic fields.

    NASA Technical Reports Server (NTRS)

    Siscoe, G. L.; Goldstein, B.

    1973-01-01

    Two basic interaction modes have been identified: (1) deflection currents that close above the surface, typified by a subsurface dipole with its axis perpendicular to the surface, and (2) deflection currents that intersect the lunar surface, typified by a subsurface dipole with its axis parallel to the surface. The first results in a compression of the lunar field and, if it is strong enough, can stop the wind above the surface. The extent of compression depends on how much the wind is slowed before striking the surface. The second mode results in a small deflection of the wind. In both modes, charging up of the surface is important. The effects of discharging the surface charge through the photolayer and the lunar crust are found to be unimportant for typical lunar parameters.

  14. The relationship between hurricane wind fields and the associated disturbance in US forest ecosystems

    NASA Astrophysics Data System (ADS)

    Negron Juarez, R. I.; Chambers, J. Q.; Hurtt, G. C.; Fisk, J. P.

    2011-12-01

    Tropical cyclones are recurrent in the U. S. Gulf Coast and produce drastic disturbance to the forest ecosystem by altering forest structure, species composition, nutrient cycling, biomass accumulation, etc. The recurrent characteristics of these events demand a rapid yet reliable assessment of forest disturbance in order to provide better management decisions, as well as to evaluate damage to the landscape, biomass loss and the associated impacts to the regional carbon budget. In this study we present a methodology for rapid assessment of forest disturbance produced by tropical cyclones based on maximum sustained wind swaths (H*wind), MODIS (Moderate Resolution Imaging Spectroradiometer)-derived disturbances and field-measured tree mortality collected in Gulf Coast forests. MODIS images in May (the month of maximum greenness) before the disturbance and in May of the year following the disturbance were processed using spectral mixture analysis (SMA) using image derived end-members. The changes in non-photosynthetic vegetation (ΔNPV, related to wood, dead vegetation and surface litter) from one year to the next was used as the disturbance metric. A strong correlation was found between H*wind and MODIS ΔNPV for hurricanes Charley (2004), Katrina (2005), Rita (2005), and Gustav (2008). In turn, MODIS ΔNPV was shown to have a strong correlation with field-measured mortality. The forest disturbance estimates based on hurricane wind-field and MODIS ΔNPV agree with those published in our previous studies. This study establishes an important relationship that could be incorporated into earth system models to improve our understanding of the effect of tropical cyclones on terrestrial ecosystems and their associated feedbacks within the climate system.

  15. Cooperative field test program for wind systems

    SciTech Connect

    Bollmeier, W.S. II; Dodge, D.M.

    1992-03-01

    The objectives of the Federal Wind Energy Program, managed by the US Department of Energy (DOE), are (1) to assist industry and utilities in achieving a multi-regional US market penetration of wind systems, and (2) to establish the United States as the world leader in the development of advanced wind turbine technology. In 1984, the program conducted a series of planning workshops with representatives from the wind energy industry to obtain input on the Five-Year Research Plan then being prepared by DOE. One specific suggestion that came out of these meetings was that the federal program should conduct cooperative research tests with industry to enhance the technology transfer process. It was also felt that the active involvement of industry in DOE-funded research would improve the state of the art of wind turbine technology. DOE established the Cooperative Field Test Program (CFTP) in response to that suggestion. This program was one of the first in DOE to feature joint industry-government research test teams working toward common objectives.

  16. Contemplating Katrina's Chaos

    ERIC Educational Resources Information Center

    Roach, Ronald

    2005-01-01

    To get some notion of how deeply scholars have been affected by Hurricane Katrina, one might look to someone like Dr. Erma Lawson, a medical sociologist from the University of North Texas. Lawson, who has coordinated the assistance efforts for the Association of Black Sociologists, has not hesitated to call on colleagues, graduate students, civil…

  17. The Katrina Kids

    ERIC Educational Resources Information Center

    Meyer, B. L.

    2007-01-01

    As the second anniversary of Hurricane Katrina rolls in, thoughts return again to those bleak days, watching people cling to their rooftops, waiting for a hand. Marking milestones, celebrating small victories, and sharing stories when things work out is a big part of life for those who work to support and connect families of children with…

  18. Lessons from Katrina

    ERIC Educational Resources Information Center

    Albrecht, Kay

    2005-01-01

    In this article, the author relates the lessons she learned from Hurricane Katrina. During the first few days after the hurricane, it took 2,500 volunteers per hour around the clock to do what needed to be done. That included medical volunteers; crisis counselors and mental health professionals; and volunteers to distribute water and snacks, serve…

  19. "Keeping it Real -High School Science Curriculum"- Hurricane Katrina and BP Oil Spill inspire creative curriculum by Dave Jungblut, Oakcrest High School Science Teacher, Mays Landing, NJ

    NASA Astrophysics Data System (ADS)

    Jungblut, D.

    2011-12-01

    After Hurricane Katrina devastated Gulf Coast homes in 2005, Oakcrest High School science teacher and geologist, Dave Jungblut, traveled from Gulfport to Ocean Springs, Mississippi and conducted research to determine whether property damage was caused by wind or water. Jungblut wrote several studies, " Katrina Straight- Line Wind Field Study", "Applying Research to Practical Use for Hurricane Katrina Homeowners", and "Hurricane Katrina Wind Study" proving wind damage. Jungblut's research, done pro bono, helped thousands of homeowner's in the Mississippi area be reimbursed by insurance companies for wind damage caused by Hurricane Katrina http://www.hurricanekatrinastudy.com/ Jungblut incorporated his extensive data, in a high school curriculum that is now part of the science program he teaches each year. In January 2010, Jungblut presented "Hurricane Forensics" curriculum at the Rutgers Center for Mathematics, Science and Computer January 2009 Workshop http://www.dimacs.rutgers.edu/wst/. Through labs and creative hands-on activities, Jungblut challenged his students to analyze the photographic evidence, and data he collected, for themselves. Jungblut taught his students how to use geologic and forensic inquiry techniques to discover the difference between straight-line winds from microburst activity. The students applied the concept of the Geological Principle of Relative Dating, to determine the sequence of events that happened during Hurricane Katrina. They built model structures, which were subjected to wind and water forces to better understand the effects of these phenomena, Finally, the students evaluated local and worldwide environmental issues, such as land use risks and benefits, in the face of global warming, In the spring of 2010 when the BP Oil Spill occurred, Jungblut realized, another opportunity to bring real world issues into the classroom. After exploring scientific concepts relating to this environmental crisis, Jungblut challenged his students to

  20. Wind Field Measurements With Airborne Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Menzies, Robert T.

    1999-01-01

    In collaboration with lidar atmospheric remote sensing groups at NASA Marshall Space Flight Center and National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory, we have developed and flown the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) lidar on the NASA DC-8 research aircraft. The scientific motivations for this effort are: to obtain measurements of subgrid scale (i.e. 2-200 km) processes and features which may be used to improve parameterizations in global/regional-scale models; to improve understanding and predictive capabilities on the mesoscale; and to assess the performance of Earth-orbiting Doppler lidar for global tropospheric wind measurements. MACAWS is a scanning Doppler lidar using a pulsed transmitter and coherent detection; the use of the scanner allows 3-D wind fields to be produced from the data. The instrument can also be radiometrically calibrated and used to study aerosol, cloud, and surface scattering characteristics at the lidar wavelength in the thermal infrared. MACAWS was used to study surface winds off the California coast near Point Arena, with an example depicted in the figure below. The northerly flow here is due to the Pacific subtropical high. The coastal topography interacts with the northerly flow in the marine inversion layer, and when the flow passes a cape or point that juts into the winds, structures called "hydraulic expansion fans" are observed. These are marked by strong variation along the vertical and cross-shore directions. The plots below show three horizontal slices at different heights above sea level (ASL). Bottom plots are enlargements of the area marked by dotted boxes above. The terrain contours are in 200-m increments, with the white spots being above 600-m elevation. Additional information is contained in the original.

  1. Comparison Between Field Data and NASA Ames Wind Tunnel Data

    SciTech Connect

    Corbus, D.

    2005-11-01

    The objective of this analysis is to compare the measured data from the NASA Ames wind tunnel experiment to those collected in the field at the National Wind Technology Center (NWTC) with the same turbine configuration. The results of this analysis provide insight into what measurements can be made in the field as opposed to wind tunnel testing.

  2. Cloud Spirals and Outflow in Tropical Storm Katrina

    NASA Technical Reports Server (NTRS)

    2005-01-01

    On Tuesday, August 30, 2005, NASA's Multi-angle Imaging SpectroRadiometer retrieved cloud-top heights and cloud-tracked wind velocities for Tropical Storm Katrina, as the center of the storm was situated over the Tennessee valley. At this time Katrina was weakening and no longer classified as a hurricane, and would soon become an extratropical depression. Measurements such as these can help atmospheric scientists compare results of computer-generated hurricane simulations with observed conditions, ultimately allowing them to better represent and understand physical processes occurring in hurricanes.

    Because air currents are influenced by the Coriolis force (caused by the rotation of the Earth), Northern Hemisphere hurricanes are characterized by an inward counterclockwise (cyclonic) rotation towards the center. It is less widely known that, at high altitudes, outward-spreading bands of cloud rotate in a clockwise (anticyclonic) direction. The image on the left shows the retrieved cloud-tracked winds as red arrows superimposed across the natural color view from MISR's nadir (vertical-viewing) camera. Both the counter-clockwise motion for the lower-level storm clouds and the clockwise motion for the upper clouds are apparent in these images. The speeds for the clockwise upper level winds have typical values between 40 and 45 m/s (144-162 km/hr). The low level counterclockwise winds have typical values between 7 and 24 m/s (25-86 km/hr), weakening with distance from the storm center. The image on the right displays the cloud-top height retrievals. Areas where cloud heights could not be retrieved are shown in dark gray. Both the wind velocity vectors and the cloud-top height field were produced by automated computer recognition of displacements in spatial features within successive MISR images acquired at different view angles and at slightly different times.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the

  3. Wind loads on flat plate photovoltaic array fields (nonsteady winds)

    NASA Technical Reports Server (NTRS)

    Miller, R. D.; Zimmerman, D. K.

    1981-01-01

    Techniques to predict the dynamic response and the structural dynamic loads of flat plate photovoltaic arrays due to wind turbulence were analyzed. Guidelines for use in predicting the turbulent portion of the wind loading on future similar arrays are presented. The dynamic response and the loads dynamic magnification factor of the two array configurations are similar. The magnification factors at a mid chord and outer chord location on the array illustrated and at four points on the chord are shown. The wind tunnel test experimental rms pressure coefficient on which magnification factors are based is shown. It is found that the largest response and dynamic magnification factor occur at a mid chord location on an array and near the trailing edge. A technique employing these magnification factors and the wind tunnel test rms fluctuating pressure coefficients to calculate design pressure loads due to wind turbulence is presented.

  4. The Astrobiology Field Guide in World Wind

    NASA Astrophysics Data System (ADS)

    Scalice, D. M.

    2004-12-01

    In collaboration with the Australian Centre for Astrobiology (ACA), and NASA Learning Technologies (NLT), and utilizing the powerful visualization capabilities of their "World Wind" software, the NASA Astrobiology Institute (NAI) is crafting a prototype "Astrobiology Field Guide" to bring the field experiences and stories of astrobiology science to the public and classrooms around the world. The prototype focuses on one region in particular - The Pilbara in Western Australia. This first Field Guide "hotspot" is an internationally recognized area hosting the best known example of the earliest evidence of life on Earth - a stromatolitic chert precipitation in the 3.45 Ga Warrawoona Group. The goal of the Astrobiology Field Guide is to engage students of all ages with the ongoing field expeditions of today's astrobiologists as they explore the ends of the Earth searching for clues to life's origin, evolution, and distribution in the Universe. The NAI hopes to expand this Field Guide to include many more astrobiologically relevant areas across the globe such as Cuatro Cienegas in Mexico, the Rio Tinto in Spain, Yellowstone National Park in the US, and the Lost City hydrothermal vent field on the mid-Atlantic ridge - and possibly sites on Mars. To that end, we will be conducting feasibility studies and evaluations with informal and formal education contacts. The Astrobiology Field Guide is also serving as a cornerstone to educational materials being developed focused on the Pilbara region for use in classrooms in Australia, the UK, and potentially the US. These materials are being developed by the Australian Centre for Astrobiology, and the ICT Innovations Centre at Macquarie University in Sydney, in collaboration with the NAI and the Centre for Astronomy and Science Education at the University of Glamorgan in the UK.

  5. Wind Field Predictions for the Columbia Gorge and the Goodnoe Hills Wind Turbine Site.

    SciTech Connect

    Veenhuizen, Scott D.; Lin, Jung-Tai.

    1980-08-01

    Numerical estimates of the long term seasonal mean wind speeds, wind directions, and available wind power density were conducted for comparison with the results of field wind measurements obtained by the Bonneville Power Administration for the Columbia Gorge region along the Oregon-Washngton border. The authors had previously used the numerical method of estimating wind flows in complex terrain to identify high wind energy areas within the Olympic Peninsula and Northern Cascade regions of the State of Washington. The numerical technique was used as a generalized wind prospecting tool to provide the link between regional assessments and on-site biological or geomorphological indicators of mean wind speeds and available wind energy. The wind flow model used is a two dimensional model based upon simplified hydrodynamical equations describing the fluid and thermodynamic motion of the atmosphere.

  6. Mod-2 wind turbine field operations experiment

    NASA Technical Reports Server (NTRS)

    Gordon, L. H.

    1985-01-01

    The three-machine, 7.5 MW Goodnoe Hills located near Goldendale, Washington and is now in a research/experimental operations phase that offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid; and the environment. Following a brief description of the turbine and project history, this paper addresses major problem areas and research and development test results. Field operations, both routine and nonroutine, are discussed. Routine operation to date has produced over 13,379,000 KWh of electrical energy during 11,064 hr of rotation. Nonroutine operation includes suspended activities caused by a crack in the low speed shaft that necessitated a redesign and reinstallation of this assembly on all three turbines. With the world's largest cluster back in full operation, two of the turbines will be operated over the next years to determine their value as energy producer. The third unit will be used primarily for conducting research tests requiring configuration changes to better understand the wind turbine technology. Technical areas summarized pertain to system performance and enhancements. Specific research tests relating to acoustics, TV interference, and wake effects conclude the paper.

  7. Shelf sediment transport during hurricanes Katrina and Rita

    NASA Astrophysics Data System (ADS)

    Xu, Kehui; Mickey, Rangley C.; Chen, Qin; Harris, Courtney K.; Hetland, Robert D.; Hu, Kelin; Wang, Jiaze

    2016-05-01

    Hurricanes can greatly modify the sedimentary record, but our coastal scientific community has rather limited capability to predict hurricane-induced sediment deposition. A three-dimensional sediment transport model was developed in the Regional Ocean Modeling System (ROMS) to study seabed erosion and deposition on the Louisiana shelf in response to Hurricanes Katrina and Rita in the year 2005. Sensitivity tests were performed on both erosional and depositional processes for a wide range of erosional rates and settling velocities, and uncertainty analysis was done on critical shear stresses using the polynomial chaos approximation method. A total of 22 model runs were performed in sensitivity and uncertainty tests. Estimated maximum erosional depths were sensitive to the inputs, but horizontal erosional patterns seemed to be controlled mainly by hurricane tracks, wave-current combined shear stresses, seabed grain sizes, and shelf bathymetry. During the passage of two hurricanes, local resuspension and deposition dominated the sediment transport mechanisms. Hurricane Katrina followed a shelf-perpendicular track before making landfall and its energy dissipated rapidly within about 48 h along the eastern Louisiana coast. In contrast, Hurricane Rita followed a more shelf-oblique track and disturbed the seabed extensively during its 84-h passage from the Alabama-Mississippi border to the Louisiana-Texas border. Conditions to either side of Hurricane Rita's storm track differed substantially, with the region to the east having stronger winds, taller waves and thus deeper erosions. This study indicated that major hurricanes can disturb the shelf at centimeter to meter levels. Each of these two hurricanes suspended seabed sediment mass that far exceeded the annual sediment inputs from the Mississippi and Atchafalaya Rivers, but the net transport from shelves to estuaries is yet to be determined. Future studies should focus on the modeling of sediment exchange between

  8. Field Tests of Wind Turbine Unit with Tandem Wind Rotors and Double Rotational Armatures

    NASA Astrophysics Data System (ADS)

    Galal, Ahmed Mohamed; Kanemoto, Toshiaki

    This paper discusses the field tests of the wind turbine unit, in which the front and the rear wind rotors drive the inner and the outer armatures of the synchronous generator. The wind rotors were designed conveniently by the traditional procedure for the single wind rotor, where the diameters of the front and the rear wind rotors are 2 m and 1.33 m. The tests were done on a pick-up type truck driven straightly at constant speed. The rotational torque of the unit is directly proportional to the induced electric current irrespective of the rotational speeds of the wind rotors, while the induced voltage is proportional to the relative rotational speed. The performance of the unit is significantly affected not only by the wind velocity, but also by the blade setting angles of both wind rotors and the applied load especially at lower wind velocity.

  9. Wind loads on flat plate photovoltaic array fields

    NASA Technical Reports Server (NTRS)

    Miller, R. D.; Zimmerman, D. K.

    1981-01-01

    The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads. The arrays located at the outer boundary of an array field have a protective influence on the interior arrays of the field. A significant decrease of the array wind loads were recorded in the wind tunnel test on array panels located behind a fence and/or interior to the array field compared to the arrays on the boundary and unprotected from the wind. The magnitude of this decrease was the same whether caused by a fence or upwind arrays.

  10. A field study of wind over a simulated block building

    NASA Technical Reports Server (NTRS)

    Frost, W.; Shahabi, A. M.

    1977-01-01

    A full-scale field study of the wind over a simulated two-dimensional building is reported. The study develops an experiment to investigate the structure and magnitude of the wind fields. A description of the experimental arrangement, the type and expected accuracy of the data, and the range of the data are given. The data are expected to provide a fundamental understanding of mean wind and turbulence structure of the wind field around the bluff body. Preliminary analysis of the data demonstrates the reliability and completeness of the data in this regard.

  11. Diagnostic Mass-Consistent Wind Field Monte Carlo Dispersion Model

    Energy Science and Technology Software Center (ESTSC)

    1991-01-01

    MATHEW generates a diagnostic mass-consistent, three-dimensional wind field based on point measurements of wind speed and direction. It accounts for changes in topography within its calculational domain. The modeled wind field is used by the Langrangian ADPIC dispersion model. This code is designed to predict the atmospheric boundary layer transport and diffusion of neutrally bouyant, non-reactive species as well as first-order chemical reactions and radioactive decay (including daughter products).

  12. A comparison of predicted and observed turbulent wind fields present in natural and internal wind park environments

    SciTech Connect

    Kelly, N D; Wright, A D

    1991-10-01

    This paper assesses the accuracy of simulated wind fields for both the natural flow and that within a wind park environment. The simulated fields are compared with the observed ones in both the time and frequency domains. Actual measurements of the wind fields and the derived kinematic scaling parameters upwind and downwind of a large San Gorgonio Pass wind park are used. The deviations in the modeled wind field from the observed are discussed. 10 refs., 6 figs., 2 tabs.

  13. Interplanetary stream magnetism: Kinematic effects. [solar magnetic fields and wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Barouch, E.

    1974-01-01

    The particle density, and the magnetic field intensity and direction are calculated in corotating streams of the solar wind, assuming that the solar wind velocity is constant and radial and that its azimuthal variations are not two rapid. The effects of the radial velocity profile in corotating streams on the magnetic fields were examined using kinematic approximation and a variety of field configurations on the inner boundary. Kinematic and dynamic effects are discussed.

  14. Probabilistic Motion Planning of Balloons in Strong, Uncertain Wind Fields

    NASA Technical Reports Server (NTRS)

    Wolf, Michael T.; Blackmore, Lars; Kuwata, Yoshiaki; Fathpour, Nanaz; Elfes, Alberto; Newman, Claire

    2010-01-01

    This paper introduces a new algorithm for probabilistic motion planning in arbitrary, uncertain vector fields, with emphasis on high-level planning for Montgolfiere balloons in the atmosphere of Titan. The goal of the algorithm is to determine what altitude--and what horizontal actuation, if any is available on the vehicle--to use to reach a goal location in the fastest expected time. The winds can vary greatly at different altitudes and are strong relative to any feasible horizontal actuation, so the incorporation of the winds is critical for guidance plans. This paper focuses on how to integrate the uncertainty of the wind field into the wind model and how to reach a goal location through the uncertain wind field, using a Markov decision process (MDP). The resulting probabilistic solutions enable more robust guidance plans and more thorough analysis of potential paths than existing methods.

  15. Measurements of lunar magnetic field interaction with the solar wind.

    NASA Technical Reports Server (NTRS)

    Dyal, P.; Parkin, C. W.; Snyder, C. W.; Clay, D. R.

    1972-01-01

    Study of the compression of the remanent lunar magnetic field by the solar wind, based on measurements of remanent magnetic fields at four Apollo landing sites and of the solar wind at two of these sites. Available data show that the remanent magnetic field at the lunar surface is compressed as much as 40% above its initial value by the solar wind, but the total remanent magnetic pressure is less than the stagnation pressure by a factor of six, implying that a local shock is not formed.

  16. Brushless exciters using a high temperature superconducting field winding

    DOEpatents

    Garces, Luis Jose; Delmerico, Robert William; Jansen, Patrick Lee; Parslow, John Harold; Sanderson, Harold Copeland; Sinha, Gautam

    2008-03-18

    A brushless exciter for a synchronous generator or motor generally includes a stator and a rotor rotatably disposed within the stator. The rotor has a field winding and a voltage rectifying bridge circuit connected in parallel to the field winding. A plurality of firing circuits are connected the voltage rectifying bridge circuit. The firing circuit is configured to fire a signal at an angle of less than 90.degree. or at an angle greater than 90.degree.. The voltage rectifying bridge circuit rectifies the AC voltage to excite or de-excite the field winding.

  17. Structure of magnetic field in the solar wind

    NASA Technical Reports Server (NTRS)

    Chertkov, A. D.

    1995-01-01

    This work is concerned with empirical data on magnetic field in the solar wind in frame of a concept of dissipative solar wind, developed in papers (Solar Wind 7 Conf., Pergamon Press, 1992, 165 and 1992 STEP/5th COSPAR Coll. Pergamon Press, 1994, 117; 235; 803). Interplanetary magnetic fields should be classified with respect to their origin. It is very important for all the theoretical problems from the necessity to specify correctly boundary and initial conditions: the magnetic field must be sewed with its source. One should select the field, connected directly with the Sun (stretched out from it), and the field of moving electric currents. It occured central in discussion about the velocity of Alfven waves, probably warming up the solar wind, relative to the Sun, the magnetic field and solar wind plasma. The selection problem corresponds to an inverse problem and obviously has no single solution. The dissipative model of the solar wind introduce the slipping and leakage of plasma relative to magnetic field. There are no 'interplanetary current sheets' in it. But temporal fluctuations from the filamentation of electric currents play the key role. As a whole, the new concept requires the re-interpretation of main objects in the interplanetary magnetic field.

  18. Hurricane Season 2005: Katrina

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Seventeen days after Hurricane Katrina flooded New Orleans, much of the city is still under water. In this pair of images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA's Terra satellite, the affected areas can clearly be seen. The top image mosaic was acquired in April and September 2000, and the bottom image was acquired September 13, 2005. The flooded parts of the city appear dark blue, such as the golf course in the northeast corner, where there is standing water. Areas that have dried out appear light blue gray, such as the city park in the left middle. On the left side of the image, the failed 17th street canal marks a sharp boundary between flooded city to the east, and dry land to the west.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 10.4 by 7.1 kilometers Location: 30 degrees North latitude, 90.1 degrees West longitude Orientation: North at top Image Data: ASTER bands 1, 2, and 3 Original Data Resolution: 15 meters (49.2 feet) Dates Acquired: September 13, 2005

  19. Hurricane Katrina at Tulane.

    NASA Astrophysics Data System (ADS)

    McGuire, Jim

    2008-03-01

    After hurricane Katrina struck New Orleans on August 29, 2005, Tulane University closed for the fall semester. Buildings on campus were closed and armed guards were hired to protect the campus. Faculty members were not allowed access to their offices and laboratories, except for exceptional cases when a Dean went with them. Many faculty members took their research groups to other universities accepting much welcomed invitations from colleagues. Undergraduates went to other colleges and universities, which accepted the without cost and a promise not to recruit them. The university email system went down for months. Collecting information on the welfare of faculty and students was difficult. The university was run from Houston by a small handful of senior administrators. Setting up the schedule of classes for the spring 2006 semester was done without records. Most faculty returned to New Orleans after several weeks. 80% of the city was flooded. Small trailers were provided. Some lived in the FEMA trailers for two years or more. When Tulane reopened, a wide reaching Renewal Plan, worked out by the upper administration, was implemented. A new emergency preparedness plan was also developed and put in place.

  20. Scaling up from field to region for wind erosion prediction using a field-scale wind erosion model and GIS

    USGS Publications Warehouse

    Zobeck, T.M.; Parker, N.C.; Haskell, S.; Guoding, K.

    2000-01-01

    Factors that affect wind erosion such as surface vegetative and other cover, soil properties and surface roughness usually change spatially and temporally at the field-scale to produce important field-scale variations in wind erosion. Accurate estimation of wind erosion when scaling up from fields to regions, while maintaining meaningful field-scale process details, remains a challenge. The objectives of this study were to evaluate the feasibility of using a field-scale wind erosion model with a geographic information system (GIS) to scale up to regional levels and to quantify the differences in wind erosion estimates produced by different scales of soil mapping used as a data layer in the model. A GIS was used in combination with the revised wind erosion equation (RWEQ), a field-scale wind erosion model, to estimate wind erosion for two 50 km2 areas. Landsat Thematic Mapper satellite imagery from 1993 with 30 m resolution was used as a base map. The GIS database layers included land use, soils, and other features such as roads. The major land use was agricultural fields. Data on 1993 crop management for selected fields of each crop type were collected from local government agency offices and used to 'train' the computer to classify land areas by crop and type of irrigation (agroecosystem) using commercially available software. The land area of the agricultural land uses was overestimated by 6.5% in one region (Lubbock County, TX, USA) and underestimated by about 21% in an adjacent region (Terry County, TX, USA). The total estimated wind erosion potential for Terry County was about four times that estimated for adjacent Lubbock County. The difference in potential erosion among the counties was attributed to regional differences in surface soil texture. In a comparison of different soil map scales in Terry County, the generalised soil map had over 20% more of the land area and over 15% greater erosion potential in loamy sand soils than did the detailed soil map. As

  1. Covering (Up?) Katrina: Discursive Ambivalence in Coverage of Hurricane Katrina

    ERIC Educational Resources Information Center

    Berger, Aimee; Cochran, Kate

    2007-01-01

    Long before Katrina, the South functioned in the social imaginary to contain racism and poverty, and the Mason-Dixon acts then in the national imagination as a buffer to safeguard the nation from the taint of such undemocratic realities. More and more, in many countries of America, a system known as "neoliberalism" prevails; based on a…

  2. Simulation of wind performance in tropical cyclone for China's future dual-frequency wind field radar

    NASA Astrophysics Data System (ADS)

    Dou, Fangli; Yin, Honggang; Gu, Songyan

    2014-11-01

    Ocean surface wind vectors (OVW) from scatterometers have been proved to be of great benefit to marine weather analysis and numerical model prediction. Conventional single-frequency scatterometers are capable to measure substantially accurate wind fields in clear atmospheric conditions, whereas winds obtained in marine extreme weather conditions are not so satisfying due to the high wind speed saturation effect and the rain perturbation. Therefore, a dualfrequency wind field measuring radar (WIFIR) to be onboard FengYun-3E is being predesigned to obtain relatively accurate wind fields in all weather conditions, which will compensate for the single-frequency shortcomings. The purpose of this study was to investigate the potential ability of WIFIR to measure OVW in tropical cyclones. A high-fidelity forward model was developed to simulate the sea surface normalize radar cross sections (NRCS) measured by WIFIR. The wind and rain rate fields used to drive the model are generated by UWNMS cloud model for Hurricane Ivan in 2004. High-wind GMFs and a theoretical rain model, which includes attenuation and volume scattering effect, have been utilized to describe the forward model. Based on the simulation results, the impact of rain on radar measurements and a dual-frequency retrieval algorithm were studied. The dual-frequency method was shown to have the ability to obtain information of rain rates up to 30mm/hr, and acquire more accurate wind vectors than single-frequency measurements. This method will be more effective to improve wind retrieval accuracy in tropical cyclones with the synchronous observation of microwave humidity sounder (MWHS) aboard FY-3 satellite.

  3. Magnetic fields of Mars and Venus - Solar wind interactions

    NASA Technical Reports Server (NTRS)

    Ness, N. F.

    1974-01-01

    Recent USSR studies of the magnetic field and solar wind flow in the vicinity of Mars and Venus confirm earlier U.S. reports of a bow shock wave developed as the solar wind interacts with these planets. Mars 2 and 3 magnetometer experiments report the existence of an intrinsic planetary magnetic field, sufficiently strong to form a magnetopause, deflecting the solar wind around the planet and its ionosphere. This is in contrast to the case for Venus, where it is assumed to be the ionosphere and processes therein which are responsible for the solar wind deflection. An empirical relationship appears to exist between planetary dipole magnetic moments and their angular momentum for the Moon, Mars, Venus, Earth, and Jupiter. Implications for the magnetic fields of Mercury and Saturn are discussed.

  4. Hosting a Katrina Evacuee.

    NASA Astrophysics Data System (ADS)

    Hoagland, David

    2008-03-01

    No individual or institution anticipated the impact on the academic research community of hurricane Katrina. When Tulane physicist Wayne Reed asked me to host his research group just a day or two after the disaster, with no authorization or understanding of the commitment, I agreed immediately and then pondered implications. Fortunately, colleagues helped in making the commitment real, only the bureaucracy of my public university posing small hindrances. Industry was remarkably generous in providing Reed with significant ``loaner'' equipment, and amazingly, a suite of custom Reed experiments was running within weeks. At the end, the most productive collaborations for Reed seemed not to have been with my group, with its similar research, but to other groups at my institution, particularly the synthetic chemists, who gained access to methods previously unique to Tulane while offering samples previously unique to UMass. Quickly designed projects exploiting this match turned out remarkably productive. Although begun with trepidation, hosting of Reed had huge positive benefits to me and UMass, and I believe, also to Reed and Tulane. Some key lessons for the future: (i) industry has capacity and willingness to help academic research during disruption (ii) commitment of a host institution must be immediate, without a wait for formal approvals or arrangement of special funding -- delay leads only to discouragement, (iii) continuing academic progress of displaced students must come first, and (iv) intellectual synergy rather than overlap should be the basis for seeking a host. Lastly, NSF or other funding agency should consider a program directly addressing the research needs of unexpectedly disrupted academic scientists, and most particularly, graduate students who face greatly extended studies.

  5. Identification of wind fields for wave modeling near Qatar

    NASA Astrophysics Data System (ADS)

    Nayak, Sashikant; Balan Sobhana, Sandeepan; Panchang, Vijay

    2016-04-01

    Due to the development of coastal and offshore infrastructure in and around the Arabian Gulf, a large semi-enclosed sea, knowledge of met-ocean factors like prevailing wind systems, wind generated waves, and currents etc. are of great importance. Primarily it is important to identify the wind fields that are used as forcing functions for wave and circulation models for hindcasting and forecasting purposes. The present study investigates the effects of using two sources of wind-fields on the modeling of wind-waves in the Arabian Gulf, in particular near the coastal regions of Qatar. Two wind sources are considered here, those obtained from ECMWF and those generated by us using the WRF model. The wave model SWAN was first forced with the 6 hourly ERA Interim daily winds (from ECMWF) having spatial resolution of 0.125°. For the second option, wind fields were generated by us using the mesoscale wind model (WRF) with a high spatial resolution (0.1°) at every 30 minute intervals. The simulations were carried out for a period of two months (7th October-7th December, 2015) during which measurements were available from two moored buoys (deployed and operated by the Qatar Meteorological Department), one in the north of Qatar ("Qatar North", in water depth of 58.7 m) and other in the south ("Shiraouh Island", in water depth of 16.64 m). This period included a high-sea event on 11-12th of October, recorded by the two buoys where the significant wave heights (Hs) reached as high as 2.9 m (i.e. max wave height H ~ 5.22 m) and 1.9 (max wave height H ~ 3.4 m) respectively. Model results were compared with the data for this period. The scatter index (SI) of the Hs simulated using the WRF wind fields and the observed Hs was found to be about 30% and 32% for the two buoys (total period). The observed Hs were generally reproduced but there was consistent underestimation. (Maximum 27% for the high-sea event). For the Hs obtained with ERA interim wind fields, the underestimation was

  6. Lessons: Katrina and Beginning Anew

    ERIC Educational Resources Information Center

    Kirylo, James D.

    2005-01-01

    New Orleans, fondly known in better days for its spectacular cuisine, cool jazz, and good times, was the leading story on television news broadcasts the world over when a massive hurricane came. As Katrina took its destructive path, culminating in the devastating rupture of ill-prepared levee systems, the world was riveted by stories about the…

  7. Hurricane Katrina: A Teachable Moment

    ERIC Educational Resources Information Center

    Bertrand, Peggy

    2009-01-01

    This article presents suggestions for integrating the phenomenon of hurricanes into the teaching of high school fluid mechanics. Students come to understand core science concepts in the context of their impact upon both the environment and human populations. Suggestions for using information about hurricanes, particularly Hurricane Katrina, in a…

  8. The Immigrant Children of Katrina

    ERIC Educational Resources Information Center

    Reyes, Augustina H.

    2010-01-01

    In August 2005, Hurricane Katrina displaced the largest number of public school children ever affected by any disaster. Approximately 370,000 children, including 15,000 Latino/Hispanic children from Louisiana, were scattered throughout the 48 U.S. states (Landrieu, 2010; Louisiana Department of Education, 2004). Although much of the media…

  9. STEM Progress in Katrina's Wake

    ERIC Educational Resources Information Center

    Gonzales, Dana

    2008-01-01

    When Hurricane Katrina hit New Orleans in 2005, it caused a devastating impact on the Crescent City's public education system. The devastating storm and its aftermath completely wiped out the educational infrastructure of the New Orleans Public Schools, making one of the country's largest metropolitan school districts virtually disappear. Two…

  10. After Katrina, Teachers Reaching Out

    ERIC Educational Resources Information Center

    Perlmutter, David D.

    2005-01-01

    In this article, the author talks about teachers communicating with students to show willingness to listen and care. In cases of real emotional distress, he refers students to the proper campus counseling services, but after Hurricane Katrina, it broke the barriers of his disengagement from students' personal problem. He learned that in many…

  11. Higher Education in Katrina's Wake

    ERIC Educational Resources Information Center

    Fields, Cheryl

    2005-01-01

    Anyone who has ever complained that colleges and universities are highly bureaucratic entities, almost inherently incapable of moving quickly, should be gratified by what we saw in the aftermath of Hurricane Katrina. With amazing swiftness, colleges and universities across the country--from large publics to small privates to community and…

  12. Solar sources of the interplanetary magnetic field and solar wind

    NASA Technical Reports Server (NTRS)

    Levine, R. H.; Altschuler, M. D.; Harvey, J. W.

    1977-01-01

    Open magnetic field lines, those which extend from the solar photosphere to interplanetary space, are traced in the current-free (potential field) approximation using measured photospheric fields as a boundary condition. It is found that (1) only a relatively small fraction of the photospheric area connects via open field lines to the interplanetary magnetic field; (2) those photospheric areas which do contribute open field lines lie beneath coronal holes and within the boundaries of the holes as projected onto the photosphere or else between loop systems of an active region; (3) the interplanetary magnetic field in the plane of the sun's equator, essentially the field in the ecliptic plane, may connect to photospheric regions of high latitude; and (4) the fastest solar wind streams are correlated with those magnetic flux tubes which expand least in cross-sectional area over the distance between the photosphere and the coronal height where the solar wind begins.

  13. Hurricane Katrina's carbon footprint on U.S. Gulf Coast forests.

    PubMed

    Chambers, Jeffrey Q; Fisher, Jeremy I; Zeng, Hongcheng; Chapman, Elise L; Baker, David B; Hurtt, George C

    2007-11-16

    Hurricane Katrina's impact on U.S. Gulf Coast forests was quantified by linking ecological field studies, Landsat and Moderate Resolution Imaging Spectroradiometer (MODIS) image analyses, and empirically based models. Within areas affected by relatively constant wind speed, tree mortality and damage exhibited strong species-controlled gradients. Spatially explicit forest disturbance maps coupled with extrapolation models predicted mortality and severe structural damage to approximately 320 million large trees totaling 105 teragrams of carbon, representing 50 to 140% of the net annual U.S. forest tree carbon sink. Changes in disturbance regimes from increased storm activity expected under a warming climate will reduce forest biomass stocks, increase ecosystem respiration, and may represent an important positive feedback mechanism to elevated atmospheric carbon dioxide. PMID:18006740

  14. Satellite Studies of Ionospheric Electric Fields and Neutral Winds

    NASA Technical Reports Server (NTRS)

    Fejer, Bela G.

    2002-01-01

    We have studied mid- and low-latitude electrodynamic and neutral thermospheric dynamic processes using measurements on board the AE-E, DE-2, and UARS (Upper Atmosphere Research Satellite) satellites, and global convection and general circulation models. These studies have determined the morphology of the equatorial zonal electric fields, the response of equatorial plasma irregularities to magnetospheric disturbances, and the time dependent response of the mid- and low latitude electric fields to magnetospheric disturbances. We have also used extensive F region zonal and meridional wind data obtained by Wind Imaging Interferometer (WINDII) instrument on board the UARS to study the latitudinal dependence of daytime disturbance winds during magnetically disturbed periods and the general characteristics of the global thermospheric disturbance wind system during geomagnetically active periods. This project has supported the PhD thesis research of John Emmert.

  15. Finding a way back home: a spirituality of exile after Hurricane Katrina.

    PubMed

    DeMoor, Emily Ann

    2009-03-01

    Three years ago breath took the form of Hurricane Katrina and passed through our bodies and our lives, leaving us forever changed. We all breathed her, but for those of us living on the Gulf Coast our encounter with Katrina was more intimate, our breathing more conscious, our memory more charged, our lives forever changed. My story takes me from the winds of Hurricane Katrina blasting through the Gulf Coast, through the tube of a machine that helped keep my son's lung expanded, through the Sinai dessert and the valley of the dry bones, through the in-between spaces of grounded groundlessness, to the forests and rivers of the Berskhire Mountains, where I have relocated and started my life over. My spiritual journey "home" is a dynamic story of Earth, wind, fire, water, flesh, and Spirit. PMID:19229630

  16. Binary stellar winds. [flow and magnetic field interactions

    NASA Technical Reports Server (NTRS)

    Siscoe, G. L.; Heinemann, M. A.

    1974-01-01

    Stellar winds from a binary star will interact with each other along a contact discontinuity. We discuss qualitatively the geometry of the flow and field resulting from this interaction in the simplest case where the stars and winds are identical. We consider the shape of the critical surface (defined as the surface where the flow speed is equal to the sound speed) as a function of stellar separation and the role of shock waves in the flow field. The effect of stellar spin and magnetic sectors on the field configuration is given. The relative roles of mass loss and magnetic torque in the evolution of orbital parameters are discussed.

  17. Binary stellar winds. [flow and magnetic field geometry

    NASA Technical Reports Server (NTRS)

    Siscoe, G. L.; Heinemann, M. A.

    1974-01-01

    Stellar winds from a binary star pair will interact with each other along a contact discontinuity. We discuss qualitatively the geometry of the flow and field resulting from this interaction in the simplest case where the stars and winds are identical. We consider the shape of the critical surface (defined as the surface where the flow speed is equal to the sound speed) as a function of stellar separation and the role of shock waves in the flow field. The effect of stellar spin and magnetic sectors on the field configuration is given. The relative roles of mass loss and magnetic torque in the evolution of orbital parameters is discussed.

  18. On Stellar Wind Bow Shocks with External Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Wilkin, Francis P.

    2016-06-01

    Stellar wind bow shocks have been seen driven by stars of many types, from O to AGB stars as well as pulsars. Recent simulations (e.g. van Marle et al. 2014) have considered the bubble created by a stellar wind of a stationary star in a region of constant magnetic field. By applying a thin-shell formalism, I consider the problem of a stellar wind from a star moving supersonically with respect to a magnetized medium. The properties of the resulting shell are derived, and limitations to the application of the resulting solution are discussed.

  19. Extratropical transitioning in the RMS Japan typhoon wind field model

    NASA Astrophysics Data System (ADS)

    Loridan, Thomas; Scherer, Emilie; Khare, Shree

    2013-04-01

    Given its meridional extent and location within the Pacific basin, Japan is regularly impacted by strong winds from cyclones at different stages of their lifecycle. To quantify the associated risk of damage to properties, catastrophe models such as the ones developed by RMS aim to simulate wind fields from thousands of stochastic storms that extrapolate historical events. In a recent study using 25 years of reanalysis data, Kitabatake (2011) estimated that 40 % of all Pacific tropical cyclones completed their transition as an extra tropical system. From a cat modelling point of view it is the increase in wind field asymmetry observed during these transitioning episodes that is critical, with examples like typhoon Tokage in 2004 showing the potential for damaging gusts on both sides of the storm track. In this context a compromise has to be found between the need for complex numerical models able to simulate wind field variability around the cyclone during its entire evolution, and obvious running time constrains. The RMS wind field model is based on an optimized version of the Willoughby parametric profile (Willoughby et al., 2006) which requires calibration against targets representative of cyclone wind fields throughout their lifecycle. We here present the different sources of data involved in the development of this model. This includes (1) satellite products to characterize wind fields from fully tropical storms, (2) high resolution simulations of key transitioning events using the WRF mesoscale model to complement the database at other stages (i.e. for transitioning and fully extra tropical wind fields), and (3) reanalysis data which can be used with Hart (2003)'s cyclone phase space methodology to provide an estimate of the mean duration of transitioning episodes in the Pacific. Kitabatake, N., 2011: Climatology of extratropical transition of tropical cyclones in the Western North Pacific defined by using cyclone phase space. J. Meteor. Soc. Japan, 89, 309

  20. Verification of wind fields by means of rain cell tracking

    NASA Astrophysics Data System (ADS)

    Herbort, F.

    2009-09-01

    VERIFICATION OF WIND FIELDS BY MEANS OF RAIN CELL TRACKING Herbort, F., Knigge, C. and Etling, D, Institute of Meteorology and Climatology, Leibniz University Hannover,Germany herbort@muk.uni-hannover.de The regional weather forecast model COSMO-DE of the German weather service is run at a spatial resolution of 2.8 km. This results in rather detailed simulations of meteorological fields like pressure, temperature and wind. In contrast, for verification of those NWP products outside the atmospheric surface layer, only a few radiosonde stations can provide the necessary observations. In order to improve the spatial and temporal resolution of observed wind fields we propose a new method based on the motion of rain cells as observed by the German rain radar network. The radar product consist of the radar reflectivity over Germany caused by hydrometeors with a spatial resolution of about 1 km and a temporal resolution of 5 minutes. The tracking of localised radar echoes caused by post frontal showers has been used for statistical analysis of rain showers in earlier work at our institute (Weusthoff and Hauf,2008). The fields of radar reflectivity are analysed in our work by the so-called PIV (Particle Image Velocimetry) method as used in experimental fluid mechanics for obtaining velocity fields of flow phenomena. Instead of solid particles as used as tracking objects in laboratory flows we use the localised radar reflectivities caused by the rain showers as tracer particles for the PIV method. The PIV algorithm provides two dimensional wind fields in the area of Germany with a few kilometres spatial resolution. The observed wind fields are compared to the wind fields obtained by the COSMO-DE model at several vertical levels in the lowest 4 kilometres of the atmosphere. By this way we could not only obtain some estimates for the skill of the wind field forecasts of the model but also could provide information on the most suitable model level for wind forecast

  1. Coronal Magnetic Field Topology and Source of Fast Solar Wind

    NASA Technical Reports Server (NTRS)

    Guhathakurta, M.; Sittler, E.; Fisher, R.; McComas, D.; Thompson, B.

    1999-01-01

    We have developed a steady state, 2D semi-empirical MHD model of the solar corona and the solar wind with many surprising results. This model for the first time shows, that the boundary between the fast and the slow solar wind as observed by Ulysses beyond 1 AU, is established in the low corona. The fastest wind observed by Ulysses (680-780 km/s) originates from the polar coronal holes at 70 -90 deg. latitude at the Sun. Rapidly diverging magnetic field geometry accounts for the fast wind reaching down to a latitude of +/- 30 deg. at the orbit of Earth. The gradual increase in the fast wind observed by Ulysses, with latitude, can be explained by an increasing field strength towards the poles, which causes Alfven wave energy flux to increase towards the poles. Empirically, there is a direct relationship between this gradual increase in wind speed and the expansion factor, f, computed at r greater than 20%. This relationship is inverse if f is computed very close to the Sun.

  2. Construction of Solar-Wind-Like Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Roberts, Dana Aaron

    2012-01-01

    Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfven waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This paper provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the\\random character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes (discontinuities), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.

  3. Construction of solar-wind-like magnetic fields.

    PubMed

    Roberts, D Aaron

    2012-12-01

    Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the "random" character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes ("discontinuities"), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles. PMID:23368180

  4. Wind effects in solar fields with various collector designs

    NASA Astrophysics Data System (ADS)

    Paetzold, Joachim; Cochard, Steve; Fletcher, David F.; Vassallo, Anthony

    2016-05-01

    Parabolic trough power plants are often located in areas that are subjected to high wind speeds, as an open terrain without any obstructions is beneficial for the plant performance. The wind impacts both the structural requirements and the performance of the plant. The aerodynamic loads from the wind impose strong requirements on the support structure of the reflectors, and they also impact the tracking accuracy. On a thermal level the airflow around the glass envelope of the receiver tube cools its outer surface through forced convection, thereby contributing to the heat loss. Based on previous studies at the level of an individual row of collectors, this study analyses the wind effects in a full-scale solar field of different continuous and staggered trough designs. The airflow around several rows of parabolic trough collectors (PTC) is simulated at full scale in steady state simulations in an atmospheric boundary layer flow using the commercial computational fluid dynamics software ANSYSO® CFX 15.0. The effect of the wake of a collector row on the following collectors is analysed, and the aerodynamic loads are compared between the different geometries. The outermost collectors of a solar field experience the highest wind forces, as the rows in the interior of the solar field are protected from high wind speeds. While the aerodynamic forces in the interior of the solar field are almost independent of the collector shape, the deeper troughs (with large rim angles) tested in this study show a lower heat loss due to forced convection on the outer surface of the receiver tube than the shallower ones (with small rim angles) in most of the solar field.

  5. Disaster response. Natural disaster: Katrina.

    PubMed

    McSwain, Norman E

    2010-07-01

    The aftermath and response to a disaster can be divided into four phases. The importance of each depends on the length of time without resupply and the resources that are required. This in turn depends on the time span of the disaster; the area involved; the number of the population affected; the resupply available; the extent of the devastation; and the size of the evacuation. The above phases are discussed using hurricane Katrina as an example. The phases are as follows: immediate response, evacuation, backfill and resupply, and restoration. The restoration phase is usually the longest and requires the most resources. This article addresses the situation of Katrina, the mistakes that were made, the lessons that were learned, and the solutions that are needed. Appropriate training and practice are required for all participants using realistic scenarios. PMID:20582507

  6. ENVIRONMENTAL CONDITIONS IN NORTHERN GULF OF MEXICO COASTAL WATERS FOLLOWING HURRICANE KATRINA

    EPA Science Inventory

    On the morning of August 29, 2005 Hurricane Katrina struck the coast of Louisiana, between New Orleans and Biloxi, Mississippi, as a strong category three hurricane on the Saffir-Simpson scale. The massive winds and flooding had the potential for a tremendous environmental impac...

  7. Lessons Learned from a Bout with Hurricane Katrina: The Delgado College Community Story

    ERIC Educational Resources Information Center

    Johnson, Alex B.; Nolan, Gayle; Siegrist, Cynthia

    2006-01-01

    When Hurricane Katrina struck the Gulf Coast on August 29, 2005, it inflicted wind and flooding damage on all but one of the five campuses and centers of Delgado Community College, the oldest and largest two-year institution in Louisiana. Hardest hit was Delgado's main location, the City Park Campus in New Orleans, where three to six feet of flood…

  8. Prediction of Ground Magnetic Field Fluctuations from Upstream Solar Wind

    NASA Astrophysics Data System (ADS)

    Weigel, R. S.; Vassiliadis, D.; Horton, W.; Klimas, A. J.

    2001-12-01

    A study of the predictability of temporal fluctuations in auroral--zone ground magnetic fields is presented. The fluctuation measure considered is the absolute value of the horizontal field time derivative (dH/dt) averaged over a 15--30~minute interval. This averaging time allows for a prediction lead time of approximately 30--45~minutes, depending on the solar wind speed. The fluctuation level is predicted using a neural network mapping of solar wind plasma and field data from the ACE satellite. Various solar wind inputs to the network are considered to determine which variables contain the most information, or drives, ground magnetic field fluctuations. The predictability of ground magnetic field fluctuations, which are responsible for ground induction currents (GICs), is shown to depend strongly on both local time and latitude. For some magnetometers, the predictability is found to be highest at local times that have the highest average fluctuation level and lowest at local times that have the lowest average fluctuation level. A maximum of 50% of the variability in a time series composed of 30~minute averages of |dH/dt| can be explained by the solar wind. When time delayed values of the fluctuation level at nearby magnetometer stations are included, up to 70% of of the variance in the |dH/dt| time series can be predicted.

  9. Model-based estimation of wind fields over the ocean from wind scatterometer measurements. I - Development of the wind field model. II - Model parameter estimation

    NASA Technical Reports Server (NTRS)

    Long, David G.; Mendel, Jerry M.

    1990-01-01

    Techniques for the determination of near-surface mesoscale ocean wind fields on the basis of satellite scatterometer data are developed and demonstrated. The derivation of normal-boundary and parameterized-boundary-condition (PBC) wind-field models is outlined, and results from a simulation performed to estimate the model errors are presented in tables. It is shown that the PBC model provides accurate results while minimizing the number of unknowns. After a review of the principles of scatterometry and an analysis of scatterometer measurement noise, an objective function for the measurement parameters is developed and optimized on the basis of gradient search with initial values computed from pointwise wind estimates. The model is then applied to data from a simulation of the NASA Scatterometer (Li et al., 1984), and the results are presented in extensive graphs. The feasibility of model-based wind-field estimation and the appropriateness of the PBC model are demonstrated.

  10. Hurricane Katrina as a "teachable moment"

    NASA Astrophysics Data System (ADS)

    Glantz, M. H.

    2008-04-01

    By American standards, New Orleans is a very old, very popular city in the southern part of the United States. It is located in Louisiana at the mouth of the Mississippi River, a river which drains about 40% of the Continental United States, making New Orleans a major port city. It is also located in an area of major oil reserves onshore, as well as offshore, in the Gulf of Mexico. Most people know New Orleans as a tourist hotspot; especially well-known is the Mardi Gras season at the beginning of Lent. People refer to the city as the "Big Easy". A recent biography of the city refers to it as the place where the emergence of modern tourism began. A multicultural city with a heavy French influence, it was part of the Louisiana Purchase from France in early 1803, when the United States bought it, doubling the size of the United States at that time. Today, in the year 2007, New Orleans is now known for the devastating impacts it withstood during the onslaught of Hurricane Katrina in late August 2005. Eighty percent of the city was submerged under flood waters. Almost two years have passed, and many individuals and government agencies are still coping with the hurricane's consequences. And insurance companies have been withdrawing their coverage for the region. The 2005 hurricane season set a record, in the sense that there were 28 named storms that calendar year. For the first time in hurricane forecast history, hurricane forecasters had to resort to the use of Greek letters to name tropical storms in the Atlantic and Gulf (Fig.~1). Hurricane Katrina was a Category 5 hurricane when it was in the middle of the Gulf of Mexico, after having passed across southern Florida. At landfall, Katrina's winds decreased in speed and it was relabeled as a Category 4. It devolved into a Category 3 hurricane as it passed inland when it did most of its damage. Large expanses of the city were inundated, many parts under water on the order of 20 feet or so. The Ninth Ward, heavily

  11. A Comparative Study of Stationary and Non-stationary Wind Models Using Field Measurements

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Hui, Michael C. H.; Xu, Y. L.

    2007-01-01

    We present a comparative study of the conventional stationary wind speed model and a newly proposed non-stationary wind speed model using field measurements. The concept of, and the differences between, the two wind models are briefly reviewed. Wind data recorded by a field measurement system for wind turbulence parameters (FMS-WTP) of 1-year duration are analyzed using the two wind models. Comparisons were made between the wind characteristics obtained from the two models, including hourly mean wind speed, turbulence intensity, the wind spectrum, integral length scale, root coherence function and probability density function. The effects of wind types (monsoon or typhoon), statistical properties (stationary or non-stationary), and surface roughness (open-sea fetch or overland fetch) on wind characteristics are discussed. The comparative study demonstrates that the non-stationary wind model appears to be more appropriate than the conventional stationary wind speed model for characterizing turbulent winds of one-hour duration over complex terrain.

  12. Efficient Low-Speed Flight in a Wind Field

    NASA Technical Reports Server (NTRS)

    Feldman, Michael A.

    1996-01-01

    A new software tool was needed for flight planning of a high altitude, low speed unmanned aerial vehicle which would be flying in winds close to the actual airspeed of the vehicle. An energy modeled NLP (non-linear programming) formulation was used to obtain results for a variety of missions and wind profiles. The energy constraint derived included terms due to the wind field and the performance index was a weighted combination of the amount of fuel used and the final time. With no emphasis on time and with no winds the vehicle was found to fly at maximum lift to drag velocity, V(sub md). When flying in tail winds the velocity was less than V(sub md), while flying in head winds the velocity was higher than V(sub md). A family of solutions was found with varying times of flight and varying fuel amounts consumed which will aid the operator in choosing a flight plan depending on a desired landing time. At certain parts of the flight, the turning terms in the energy constraint equation were found to be significant. An analysis of a simpler vertical plane cruise optimal control problem was used to explain some of the characteristics of the vertical plane NLP results.

  13. Synoptic scale wind field properties from the SEASAT SASS

    NASA Technical Reports Server (NTRS)

    Pierson, W. J., Jr.; Sylvester, W. B.; Salfi, R. E.

    1984-01-01

    Dealiased SEASAT SEASAT A Scatterometer System SASS vector winds obtained during the Gulf Of Alaska SEASAT Experiment GOASEX program are processed to obtain superobservations centered on a one degree by one degree grid. The grid. The results provide values for the combined effects of mesoscale variability and communication noise on the individual SASS winds. These superobservations winds are then processed further to obtain estimates of synoptic scale vector winds stress fields, the horizontal divergence of the wind, the curl of the wind stress and the vertical velocity at 200 m above the sea surface, each with appropriate standard deviations of the estimates for each grid point value. They also explain the concentration of water vapor, liquid water and precipitation found by means of the SMMR Scanning Multichannel Microwave Radiometer at fronts and occlusions in terms of strong warm, moist air advection in the warm air sector accompanied by convergence in the friction layer. Their quality is far superior to that of analyses based on conventional data, which are shown to yield many inconsistencies.

  14. Estimating the saltation and suspension components from field wind erosion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving wind erosion models requires correct estimates of the suspended dust and saltation/creep components from field erosion events. Estimated dust emissions are used to quantify off-site effects ranging from visibility reductions to health assessments. Moreover, the saltation/creep discharge ...

  15. Magnetic Fields generated in the Solar Wind Interaction with Mars

    NASA Astrophysics Data System (ADS)

    Vennerstrom, S.; Primdahl, F.

    The solar wind interaction with Mars has revealed a complexity that provide a major challenge for planetary exploration, and which places it as a central issue of current research in space physics. The combined effect of direct interaction between the solar wind and the atmosphere and the formation of mini-magnetospheres around the strong crustal anomalies is unique in the solar system and so far largely unexplored. The most extensive set of magnetic field observations near Mars comes from more than six years of operation of the Mars Global Surveyor MAG/ER measurements. These reveal both piled-up magnetic disturbances generated in the interaction with the atmosphere as well as significant perturbations associated with a direct interaction between the solar wind and the crustal fields. While the magnetic field in the pile-up region are generally closely associated with the upstream solar wind parameters, the perturbations close to the magnetic anomalies and in the ionosphere are much more complex. Combined magnetic field and plasma observations in the martian ionosphere as proposed in the Mars Escape and Magnetic Orbiter (MEMO) are clearly needed. In addition surface magnetic observations characterizing magnetic activity at Mars are highly called for.

  16. Counterstreaming solar wind halo electron events on open field lines?

    NASA Technical Reports Server (NTRS)

    Gosling, J. T.; Mccomas, D. J.; Phillips, J. L.

    1992-01-01

    Counterstreaming solar wind halo electron events have been identified as a common 1 AU signature of coronal mass ejection events, and have generally been interpreted as indicative of closed magnetic field topologies, i.e., magnetic loops or flux ropes rooted at both ends in the Sun, or detached plasmoids. In this paper we examine the possibility that these events may instead occur preferentially on open field lines, and that counterstreaming results from reflection or injection behind interplanetary shocks or from mirroring from regions of compressed magnetic field farther out in the heliosphere. We conclude that neither of these suggested sources of counterstreaming electron beams is viable and that the best interpretation of observed counterstreaming electron events in the solar wind remains that of passage of closed field structures.

  17. Field measurements in the wake of a model wind turbine

    NASA Astrophysics Data System (ADS)

    Pol, Suhas; Taylor, Amelia; Bilbao, Argenis; Doostalab, Ali; Novoa, Santiago; Westergaard, Carsten; Hussain, Fazle; Sheng, Jian; Ren, Beibei; Giesselmann, Michael; Glauser, Mark; Castillo, Luciano

    2014-06-01

    As a first step to study the dynamics of a wind farm' we experimentally explored the flow field behind a single wind turbine of diameter 1.17 m at a hub height of 6.25 m. A 10 m tower upstream of the wind farm characterizes the atmospheric conditions and its influence on the wake evolution. A vertical rake of sonic anemometers is clustered around the hub height on a second tower' 6D downstream of the turbine. We present preliminary observations from a 1- hour block of data recorded in near-neutral atmospheric conditions. The ratio of the standard deviation of power to the inflow velocity is greater than three' revealing adverse effects of inflow turbulence on the power and load fluctuations. Furthermore' the wake defect and Reynolds stress and its gradient are pronounced at 6D. The flux of energy due to Reynolds stresses is similar to that reported in wind tunnel studies. The swirl and mixing produces a constant temperature wake which results in a density jump across the wake interface. Further field measurements will explore the dynamics of a model wind farm' including the effects of atmospheric variability.

  18. Ocean wind field measurement performance of the ERS-1 scatterometer

    NASA Technical Reports Server (NTRS)

    Hans, P.; Schuessler, H.

    1984-01-01

    The Active Microwave Instrumentation (AMI), which will be implemented on the ERS-1, is a 5.3 GHz multipurpose radar for land surface imaging, ocean wave spectrum measurement and wind observations over oceans. The imaging and wave measurements apply Synthetic Aperture Radar (SAR) techniques, while wind field detection is performed by the Scatterometer as part of the AMI. The Scatterometer system design was developed and optimized with the aid of a performance simulator. This paper, aimed at giving an overview, is presented about the: (1) ERS-1 Scatterometer system design; (2) Error budget; and the (3) Overall calibration concept.

  19. Magnetic field configurations associated with fast solar wind

    NASA Technical Reports Server (NTRS)

    Sheeley, N. R., Jr.; Wang, Y.-M.

    1991-01-01

    The implications are considered of the observed inverse correlation between solar wind speed at earth and the expansion rate of the sun-earth flux tube as it passes through the corona. It is found that the coronal expansion rate depends critically on the large-scale photospheric field distribution around the footpoint of the flux tube. The smallest expansions occur in tubes that are rooted near a local minimum in the field. This suggests that the fastest wind streams originate from regions where large coronal holes are about to break apart and from the facing edges of adjacent like-polarity holes, whose field lines converge as they transit the corona. Predictions are made which follow from the above ideas.

  20. Wind direction alias removal studies of Seasat scatterometer-derived wind fields

    NASA Technical Reports Server (NTRS)

    Wurtele, M. G.; Borowski, M.; Woiceshyn, P. M.; Peteherych, S.; Appleby, W. S.

    1982-01-01

    Seasat SASS fields for the North Atlantic were employed to test if meteorological features were discernible within the Seasat-produced wind fields, and if the features aided in determining a unique wind vector solution. Two groups were formed to work in isolation from each other until a true wind vector field was obtained for each SASS observation. The SASS data covered 1500 km swaths, and the angle of the Seasat antennas relative to the earth was known. Visible and IR data, along with surface weather stations, ship and ship buoy data were also available to the interpreters. Two-vector solutions by the two teams showed almost perfect agreement, and the alias problem was noted to reduce to a selection of two vectors 180 deg apart. Comparisons with the surface measurements in regards to wind directions resulted in agreement to within a standard deviation of 20% for direction. The SASS data is concluded to be useful for producing streamlines, isotachs, and mesoscale as well as cyclone-scale features.

  1. SMART wind turbine rotor. Design and field test

    SciTech Connect

    Berg, Jonathan Charles; Resor, Brian Ray; Paquette, Joshua A.; White, Jonathan Randall

    2014-01-01

    The Wind Energy Technologies department at Sandia National Laboratories has developed and field tested a wind turbine rotor with integrated trailing-edge flaps designed for active control of rotor aerodynamics. The SMART Rotor project was funded by the Wind and Water Power Technologies Office of the U.S. Department of Energy (DOE) and was conducted to demonstrate active rotor control and evaluate simulation tools available for active control research. This report documents the design, fabrication, and testing of the SMART Rotor. This report begins with an overview of active control research at Sandia and the objectives of this project. The SMART blade, based on the DOE / SNL 9-meter CX-100 blade design, is then documented including all modifications necessary to integrate the trailing edge flaps, sensors incorporated into the system, and the fabrication processes that were utilized. Finally the test site and test campaign are described.

  2. Prediction of the far field noise from wind energy farms

    NASA Technical Reports Server (NTRS)

    Shepherd, K. P.; Hubbard, H. H.

    1986-01-01

    The basic physical factors involved in making predictions of wind turbine noise and an approach which allows for differences in the machines, the wind energy farm configurations and propagation conditions are reviewed. Example calculations to illustrate the sensitivity of the radiated noise to such variables as machine size, spacing and numbers, and such atmosphere variables as absorption and wind direction are presented. It is found that calculated far field distances to particular sound level contours are greater for lower values of atmospheric absorption, for a larger total number of machines, for additional rows of machines and for more powerful machines. At short and intermediate distances, higher sound pressure levels are calculated for closer machine spacings, for more powerful machines, for longer row lengths and for closer row spacings.

  3. Cooperative field test program for wind systems. Final report

    SciTech Connect

    Bollmeier, W.S. II; Dodge, D.M.

    1992-03-01

    The objectives of the Federal Wind Energy Program, managed by the US Department of Energy (DOE), are (1) to assist industry and utilities in achieving a multi-regional US market penetration of wind systems, and (2) to establish the United States as the world leader in the development of advanced wind turbine technology. In 1984, the program conducted a series of planning workshops with representatives from the wind energy industry to obtain input on the Five-Year Research Plan then being prepared by DOE. One specific suggestion that came out of these meetings was that the federal program should conduct cooperative research tests with industry to enhance the technology transfer process. It was also felt that the active involvement of industry in DOE-funded research would improve the state of the art of wind turbine technology. DOE established the Cooperative Field Test Program (CFTP) in response to that suggestion. This program was one of the first in DOE to feature joint industry-government research test teams working toward common objectives.

  4. Impacts of Hurricane Katrina on floodplain forests of the Pearl River: Chapter 6A in Science and the storms-the USGS response to the hurricanes of 2005

    USGS Publications Warehouse

    Faulkner, Stephen; Barrow, Wylie; Couvillion, Brady R.; Conner, William; Randall, Lori; Baldwin, Michael

    2007-01-01

    Floodplain forests are an important habitat for Neotropical migratory birds. Hurricane Katrina passed through the Pearl River flood plain shortly after making landfall. Field measurements on historical plots and remotely sensed data were used to assess the impact of Hurricane Katrina on the structure of floodplain forests of the Pearl River.

  5. Lessons Learnt From Hurricane Katrina.

    NASA Astrophysics Data System (ADS)

    Akundi, Murty

    2008-03-01

    Hurricane Katrina devastated New Orleans and its suburbs on Monday August 29^th, 2005. The previous Friday morning, August 26, the National Hurricane Center indicated that Katrina was a Category One Hurricane, which was expected to hit Florida. By Friday afternoon, it had changed its course, and neither the city nor Xavier University was prepared for this unexpected turn in the hurricane's path. The university had 6 to 7 ft of water in every building and Xavier was closed for four months. Students and university personnel that were unable to evacuate were trapped on campus and transportation out of the city became a logistical nightmare. Email and all electronic systems were unavailable for at least a month, and all cell phones with a 504 area code stopped working. For the Department, the most immediate problem was locating faculty and students. Xavier created a list of faculty and their new email addresses and began coordinating with faculty. Xavier created a web page with advice for students, and the chair of the department created a separate blog with contact information for students. The early lack of a clear method of communication made worse the confusion and dismay among the faculty on such issues as when the university would reopen, whether the faculty would be retained, whether they should seek temporary (or permanent) employment elsewhere, etc. With the vision and determination of President Dr. Francis, Xavier was able to reopen the university in January and ran a full academic year from January through August. Since Katrina, the university has asked every department and unit to prepare emergency preparedness plans. Each department has been asked to collect e-mail addresses (non-Xavier), cell phone numbers and out of town contact information. The University also established an emergency website to communicate. All faculty have been asked to prepare to teach classes electronically via Black board or the web. Questions remain about the longer term issues of

  6. Field Wind Tunnel Assessment of the Potential for Wind Transport of Soils

    SciTech Connect

    Lancaster, Nicholas; Metzger, Steve

    2005-02-01

    This report documents a series of field experiments carried out in the Double Tracks area of the Tonopah Test Range in June, July, and August 1996 and March and July 1997. The aim of the experiments was to: (1) determine the wind speeds necessary to entrain surface particles from excavated surfaces in the study area and (2) determine dust emissions from surfaces that had been stabilized permanently by planted natural vegetation. This investigation assessed the potential for wind transport of surface soils, including resuspension and emission of dust sized particles from areas of surface heavy metal contamination, following site remediation, as well as the actual emissions from these areas. The remediation site is located in Area 73 of the Tonopah Test Range. The goal of the field experiments was to measure the velocities with which boundary layer winds might initiate dust emissions from the affected site, and to gage the effectiveness of surface stabilization procedures to prevent such emissions. Particle movement measurements were generated through the use of a portable wind tunnel laid directly on the excavated surface.

  7. Sustainability: a view from the wind-eroded field.

    PubMed

    Warren, Andrew

    2007-01-01

    This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeoaeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground (even when they are attached to dust-sized particles), and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustainability of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas (like China, the Sahel and Northwestern Europe) generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth (so that wind erosion may even improve the soil). Finally some remarks are made about environmental change in relation to sustainability. PMID:17915712

  8. Simulating Turbulent Wind Fields for Offshore Turbines in Hurricane-Prone Regions (Poster)

    SciTech Connect

    Guo, Y.; Damiani, R.; Musial, W.

    2014-04-01

    Extreme wind load cases are one of the most important external conditions in the design of offshore wind turbines in hurricane prone regions. Furthermore, in these areas, the increase in load with storm return-period is higher than in extra-tropical regions. However, current standards have limited information on the appropriate models to simulate wind loads from hurricanes. This study investigates turbulent wind models for load analysis of offshore wind turbines subjected to hurricane conditions. Suggested extreme wind models in IEC 61400-3 and API/ABS (a widely-used standard in oil and gas industry) are investigated. The present study further examines the wind turbine response subjected to Hurricane wind loads. Three-dimensional wind simulator, TurbSim, is modified to include the API wind model. Wind fields simulated using IEC and API wind models are used for an offshore wind turbine model established in FAST to calculate turbine loads and response.

  9. Measurements of electric fields in the solar wind: Interpretation difficulties

    NASA Technical Reports Server (NTRS)

    Chertkov, A. D.

    1995-01-01

    The traditionally measured electric fields in the solar wind plasma (about 1-10 mV/m) are not the natural, primordial ones but are the result of plasma-vehicle interaction. The theory of this interaction is not complete now and current interpretation of the measurements can fail. The state of fully ionized plasma depends on the entropy of the creating source and on the process in which plasma is involved. The increasing twofold of a moving volume in the solar wind (with energy transfer across its surface which is comparable with its whole internal energy) is a more rapid process than the relaxation for the pressure. The presumptive source of the solar wind creation - the induction electric field of the solar origin - has very low entropy. The state of plasma must be very far from the state of thermodynamic equilibrium. The internal energy of plasma can be contained mainly in plasma waves, resonant plasma oscillations, and electric currents. The primordial microscopic oscillating electric fields could be about 1 V/m. It can be checked by special measurements, not ruining the natural plasma state. The tool should be a dielectrical microelectroscope outside the distortion zone of the spacecraft, having been observed from the latter.

  10. Magnetic holes in the solar wind. [(interplanetary magnetic fields)

    NASA Technical Reports Server (NTRS)

    Turner, J. M.; Burlaga, L. F.; Ness, N. F.; Lemaire, J. F.

    1976-01-01

    An analysis is presented of high resolution interplanetary magnetic field measurements from the magnetometer on Explorer 43 which showed that low magnetic field intensities in the solar wind at 1 AU occur as distinct depressions or 'holes'. These magnetic holes are new kinetic-scale phenomena, having a characteristic dimension on the order of 20,000 km. They occurred at a rate of 1.5/day in the 18-day time span (March 18 to April 6, 1971) that was analyzed. Most of the magnetic holes are characterized by both a depression in the absolute value of the magnetic field, and a change in the magnetic field direction; some of these are possibly the result of magnetic merging. However, in other cases the magnetic field direction does not change; such holes are not due to magnetic merging, but might be a diamagnetic effect due to localized plasma inhomogeneities.

  11. Mental illness and suicidality after Hurricane Katrina.

    PubMed Central

    Kessler, Ronald C.; Galea, Sandro; Jones, Russell T.; Parker, Holly A.

    2006-01-01

    OBJECTIVE: To estimate the impact of Hurricane Katrina on mental illness and suicidality by comparing results of a post-Katrina survey with those of an earlier survey. METHODS: The National Comorbidity Survey-Replication, conducted between February 2001 and February 2003, interviewed 826 adults in the Census Divisions later affected by Hurricane Katrina. The post-Katrina survey interviewed a new sample of 1043 adults who lived in the same area before the hurricane. Identical questions were asked about mental illness and suicidality. The post-Katrina survey also assessed several dimensions of personal growth that resulted from the trauma (for example, increased closeness to a loved one, increased religiosity). Outcome measures used were the K6 screening scale of serious mental illness and mild-moderate mental illness and questions about suicidal ideation, plans and attempts. FINDINGS: Respondents to the post-Katrina survey had a significantly higher estimated prevalence of serious mental illness than respondents to the earlier survey (11.3% after Katrina versus 6.1% before; chi(2)1= 10.9; P < 0.001) and mild-moderate mental illness (19.9% after Katrina versus 9.7% before; chi(2)1 = 22.5; P < 0.001). Among respondents estimated to have mental illness, though, the prevalence of suicidal ideation and plans was significantly lower in the post-Katrina survey (suicidal ideation 0.7% after Katrina versus 8.4% before; chi(2)1 = 13.1; P < 0.001; plans for suicide 0.4% after Katrina versus 3.6% before; chi(2)1 = 6.0; P = 0.014). This lower conditional prevalence of suicidality was strongly related to two dimensions of personal growth after the trauma (faith in one's own ability to rebuild one's life, and realization of inner strength), without which between-survey differences in suicidality were insignificant. CONCLUSION: Despite the estimated prevalence of mental illness doubling after Hurricane Katrina, the prevalence of suicidality was unexpectedly low. The role of post

  12. Field investigation of a wake structure downwind of a VAWT (vertical-axis wind turbine) in a wind farm array

    SciTech Connect

    Liu, H.T.; Buck, J.W.; Germain, A.C.; Hinchee, M.E.; Solt, T.S.; LeRoy, G.M.; Srnsky, R.A.

    1988-09-01

    The effects of upwind turbine wakes on the performance of a FloWind 17-m vertical-axis wind turbine (VAWT) were investigated through a series of field experiments conducted at the FloWind wind farm on Cameron Ridge, Tehachapi, California. From the field measurements, we derived the velocity and power/energy deficits under various turbine on/off configurations. Much information was provided to characterize the structure of VAWT wakes and to assess their effects on the performance of downwind turbines. A method to estimate the energy deficit was developed based on the measured power deficit and the wind speed distributions. This method may be adopted for other turbine types and sites. Recommendations are made for optimizing wind farm design and operations, as well as for wind energy management. 17 refs., 66 figs., 6 tabs.

  13. Field investigation of a wake structure downwind of a VANT (Vertical-Axis Wind Turbine) in a wind farm array

    NASA Astrophysics Data System (ADS)

    Liu, H. T.; Buck, J. W.; Germain, A. C.; Hinchee, M. E.; Solt, T. S.; Leroy, G. M.; Srnsky, R. A.

    1988-09-01

    The effects of upwind turbine wakes on the performance of a FloWind 17-m vertical-axis wind turbine (VAWT) were investigated through a series of field experiments conducted at the FloWind wind farm on Cameron Ridge, Tehachapi, California. From the field measurements, we derived the velocity and power/energy deficits under various turbine on/off configurations. Much information was provided to characterize the structure of VAWT wakes and to assess their effects on the performance of downwind turbines. A method to estimate the energy deficit was developed based on the measured power deficit and the wind speed distributions. This method may be adopted for other turbine types and sites. Recommendations are made for optimizing wind farm design and operations, as well as for wind energy management.

  14. A wind tunnel application of large-field focusing schlieren

    NASA Technical Reports Server (NTRS)

    Ponton, Michael K.; Seiner, John M.; Mitchell, L. K.; Manning, James C.; Jansen, Bernard J.; Lagen, Nicholas T.

    1992-01-01

    A large-field focusing schlieren apparatus was installed in the NASA Lewis Research Center 9 by 15 foot wind tunnel in an attempt to determine the density gradient flow field of a free jet issuing from a supersonic nozzle configuration. The nozzle exit geometry was designed to reduce acoustic emissions from the jet by enhancing plume mixing. Thus, the flow exhibited a complex three-dimensional structure which warranted utilizing the sharp focusing capability of this type of schlieren method. Design considerations concerning tunnel limitations, high-speed photography, and video tape recording are presented in the paper.

  15. Solar wind magnetic field bending of Jovian dust trajectories.

    PubMed

    Zook, H A; Grün, E; Baguhl, M; Hamilton, D P; Linkert, G; Liou, J; Forsyth, R; Phillips, J L

    1996-11-29

    From September 1991 to October 1992, the cosmic dust detector on the Ulysses spacecraft recorded 11 short bursts, or streams, of dust. These dust grains emanated from the jovian system, and their trajectories were strongly affected by solar wind magnetic field forces. Analyses of the on-board measurements of these fields, and of stream approach directions, show that stream-associated dust grain masses are of the order of 10(-18) gram and dust grain velocities exceed 200 kilometers per second. These masses and velocities are, respectively, about 10(3) times less massive and 5 to 10 times faster than earlier reported. PMID:8929405

  16. Thermospheric Response to Solar Wind Electric Field Fluctuations

    NASA Astrophysics Data System (ADS)

    Perlongo, N. J.; Ridley, A. J.

    2013-12-01

    The electron density of the thermosphere is of paramount importance for radio communications and drag on low altitude satellites, particularly during geomagnetic storms. Transient enhancements of ion velocities and subsequent density and temperature increases frequently occur as a result of storm-driven solar wind electric field fluctuations. Since the Earth's dipole magnetic field is tilted and offset from the center of the planet, significant asymmetries arise that alter the thermospheric response to energy input based upon the time of day of the disturbance. This study utilizes the Global Ionosphere-Thermosphere Model (GITM) to investigate this phenomenon by enhancing the convective electric field for one hour of the day in 22 different simulations. An additional baseline run was conducted with no IMF perturbation. Furthermore, four configurations of Earth's magnetic field were considered, Internal Geomagnetic Reference Field (IGRF), a perfect dipole, a dipole tilted by 10 degrees, and a tilted and offset dipole. These runs were conducted at equinox when the amount of sunlight falling on the different hemispheres is the same. Two additional runs were conducted at the solstices for comparison. It was found that the most geo-effective times are when the poles are pointed towards the sun. The electron density, neutral density and temperature as well as the winds are explored.

  17. Wind Field and Trajectory Models for Tornado-Propelled Objects

    NASA Technical Reports Server (NTRS)

    Redmann, G. H.; Radbill, J. R.; Marte, J. E.; Dergarabedian, P.; Fendell, F. E.

    1978-01-01

    A mathematical model to predict the trajectory of tornado born objects postulated to be in the vicinity of nuclear power plants is developed. An improved tornado wind field model satisfied the no slip ground boundary condition of fluid mechanics and includes the functional dependence of eddy viscosity with altitude. Subscale wind tunnel data are obtained for all of the missiles currently specified for nuclear plant design. Confirmatory full-scale data are obtained for a 12 inch pipe and automobile. The original six degree of freedom trajectory model is modified to include the improved wind field and increased capability as to body shapes and inertial characteristics that can be handled. The improved trajectory model is used to calculate maximum credible speeds, which for all of the heavy missiles are considerably less than those currently specified for design. Equivalent coefficients for use in three degree of freedom models are developed and the sensitivity of range and speed to various trajectory parameters for the 12 inch diameter pipe are examined.

  18. Design, construction and calibration of a portable boundary layer wind tunnel for field use

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind tunnels have been used for several decades to study wind erosion processes. Portable wind tunnels offer the advantage of testing natural surfaces in the field, but they must be carefully designed to insure that a logarithmic boundary layer is formed and that wind erosion processes may develop ...

  19. StenniSphere reopens after Hurricane Katrina

    NASA Technical Reports Server (NTRS)

    2006-01-01

    StenniSphere reopened Jan. 18, 2006, almost five months after Hurricane Katrina damaged the basement of the building that houses the visitor center. Thanks to the staff's careful preparations before the storm, no artifacts or exhibits were harmed.

  20. Enhanced gauge symmetry and winding modes in double field theory

    NASA Astrophysics Data System (ADS)

    Aldazabal, G.; Graña, M.; Iguri, S.; Mayo, M.; Nuñez, C.; Rosabal, J. A.

    2016-03-01

    We provide an explicit example of how the string winding modes can be incorporated in double field theory. Our guiding case is the closed bosonic string compactified on a circle of radius close to the self-dual point, where some modes with non-zero winding or discrete momentum number become massless and enhance the U(1) × U(1) symmetry to SU(2) × SU(2). We compute three-point string scattering amplitudes of massless and slightly massive states, and extract the corresponding effective low energy gauge field theory. The enhanced gauge symmetry at the self-dual point and the Higgs-like mechanism arising when changing the compactification radius are examined in detail. The extra massless fields associated to the enhancement are incorporated into a generalized frame with Oleft(d+3,d+3right)/Oleft(d+3right)× Oleft(d+3right) structure, where d is the number of non-compact dimensions. We devise a consistent double field theory action that reproduces the low energy string effective action with enhanced gauge symmetry. The construction requires a truly non-geometric frame which explicitly depends on both the compact coordinate along the circle and its dual.

  1. Computations of wind-driven ocean-induced magnetic fields

    NASA Astrophysics Data System (ADS)

    Sachl, Libor; Einspigel, David; Martinec, Zdenek

    2016-04-01

    We present the results of computations of the secondary magnetic field induced by ocean motions. Ocean velocities are computed using the baroclinic ocean model LSOMG. The velocities are then used to determine the Lorentz force which is plugged into the magnetic induction code TLAM as a principal forcing. The TLAM is a 2D magnetic induction code based on the thin-shell approximation (Vivier et al., 2004; Tyler et al., 1997). In this approximation, the equation of magnetic induction simplifies significantly, time derivatives of main and induced magnetic fields are neglected as well as the self-induction term. The price for simplification of governing equations is the limited applicability of the resulting system. It is only suitable for slowly evolving processes. In order to meet the condition, we restrict ourselves to the wind (buoyancy) driven ocean circulation, although the LSOMG model is able to model both tidally- and wind-driven circulations. We assess the accuracy of thin-shell approximation in our setup by comparing the results with the Swarm satellite magnetic data. References Tyler, R. H., Mysak, L. A., and Oberhuber, J. M, 1997. Electromagnetic fields generated by a three dimensional global ocean circulation. J. Geophys. Res., 102, 5531-5551. Vivier, F., Meier-Reimer, E., and Tyler, R. H., 2004. Simulations of magnetic fields generated by the Antarctic Circumpolar Current at satellite altitude: Can geomagnetic measurements be used to monitor the flow? Geophys. Res. Lett., 31, L10306, doi:10.1029/2004GL019804.

  2. Distribution of magnetic field components in the solar wind plasma

    NASA Astrophysics Data System (ADS)

    Padhye, N. S.; Smith, C. W.; Matthaeus, W. H.

    2001-09-01

    We examine the probability distribution functions (PDFs) of fluctuations of magnetic field components using the Ulysses and Omnitape data sets to evaluate departures from Gaussian distributions. Functional fits as well as moment comparisons (kurtoses) are used in drawing conclusions concerning the degree of non-Gaussianity. Short-timescale fluctuations are separated, to the extent possible, from the longer-timescale variation of the mean field, and attention is paid to data selection issues such as stationarity. At the present level of comparison it seems that departures from Gaussianity of the distributions of the fluctuations are not severe. The analysis is carried out in the mean field coordinates in which the fluctuations of components are close to being uncorrelated, and it is observed that the perpendicular components are closer to being Gaussian than the parallel one. It is shown that the kurtosis is highly exaggerated when the variation of the mean field is not taken into account. We further examine the distributions of hourly magnetic field fluctuations in fast and slow solar wind at different phases in the solar cycle in order to quantitatively describe departures from the Gaussian distribution. It is found that the kurtosis lies between 2.8 and 4.8 for all components in the mean field coordinates, in both fast and slow wind and near solar maximum and near solar minimum. It appears that the distributions of fluctuations are rather more similar with regard to their degree of non-Gaussianity than might have been expected based upon the well-documented differences in the characteristics of fast and slow solar wind intervals. This suggests a robust form of statistical similarity that may be associated with either in situ or source region nonlinear effects. In addition to the distributions of the fluctuations, we present the distributions of the mean field and of the variances of the components which are more likely to be influenced by solar sources than by

  3. Magnetic Field Rotations at Kinetic Scales in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Chen, Christopher; Matteini, Lorenzo; Burgess, David; Horbury, Timothy

    2015-04-01

    The distribution of spatial angle changes in the solar wind magnetic field is usually attributed to a mixture of turbulence and other structures. Recent results have suggested that in the MHD inertial range this distribution may be scale invariant, generated by the turbulence, and consist mainly of field rotations. Here, we examine the distribution of magnetic field rotations in the smaller scale kinetic range (from ion to electron scales), where the turbulence is thought to be dissipated, using combined fluxgate/search-coil magnetometer data from Cluster. The degree of self-similarity is measured and the spatial distribution of the fluctuations at different scales is compared. At ion scales, the energy in angle rotations larger than α drops exponentially with α with e-folding ~10°, and at electron scales with e-folding

  4. Katrina Kinetics: The Physician Supply.

    PubMed

    Heckle, Mark R; Askari, Raza; Morsy, Mohamed; Ibebuogu, Uzoma N

    2016-01-01

    In the aftermath of Hurricane Katrina 10 years ago, acute changes were recognized and reported; acute kinetic destruction and desperation. Physicians performed heroically, but after the flood and the closing of hospitals, most left at least briefly. The chronic recovery began with spirit, but was uncharted and unplanned with the recognition that individual decisions were a necessity. The documentation of physician numbers of practicing doctors, residents and fellows, from the AMA as related to geography, population, and other circumstances tells an additional story of renewal, more objectively without the hype. The fall and rise of the physician population occurred, and was and is remarkable in its consistency, smaller than expected variations. Its effect generated promise for continuous chronic conditions of recovery and positive change. PMID:27598896

  5. Tracing the Effects of Hurricane Katrina on the Population of New Orleans: The Displaced New Orleans Residents Pilot Study

    PubMed Central

    Sastry, Narayan

    2009-01-01

    The Displaced New Orleans Residents Pilot Study was designed to examine the current location, well-being, and plans of people who lived in the City of New Orleans when Hurricane Katrina struck on 29 August 2005. The study is based on a representative sample of pre-Katrina dwellings in the city. Respondents were administered a short paper-and-pencil interview by mail, by telephone, or in person. The pilot study was fielded in the fall of 2006, approximately one year after Hurricane Katrina. In this paper, we describe the motivation for the pilot study, outline its design, and describe the fieldwork results using a set of fieldwork outcome rates and multivariate logistic models. We end with a discussion of the lessons learned from the pilot study for future studies of the effects of Hurricane Katrina on the population of New Orleans. The results point to the challenges and opportunities of studying this unique population. PMID:20161061

  6. Electrons on closed field lines of lunar crustal fields in the solar wind wake

    NASA Astrophysics Data System (ADS)

    Nishino, Masaki N.; Saito, Yoshifumi; Tsunakawa, Hideo; Takahashi, Futoshi; Fujimoto, Masaki; Harada, Yuki; Yokota, Shoichiro; Matsushima, Masaki; Shibuya, Hidetoshi; Shimizu, Hisayoshi

    2015-04-01

    Plasma signature around crustal magnetic fields is one of the most important topics of the lunar plasma sciences. Although recent spacecraft measurements are revealing solar-wind interaction with the lunar crustal fields on the dayside, plasma signatures around crustal fields on the night side have not been fully studied yet. Here we show evidence of plasma trapping on the closed field lines of the lunar crustal fields in the solar-wind wake, using SELENE (Kaguya) plasma and magnetic field data obtained at 14-15 km altitude from the lunar surface. In contrast to expectation on plasma cavity formation at the strong crustal fields, electron flux is enhanced above Crisium Antipode (CA) anomaly which is one of the strongest lunar crustal fields. The enhanced electron fluxes above CA are characterised by (1) occasional bi-directional field-aligned beams in the lower energy range (<150 eV) and (2) a medium energy component (150-300 eV) that has a double loss-cone distribution representing bounce motion between the two footprints of the crustal magnetic fields. The low-energy electrons on the closed field lines may come from the lunar night side surface, while supply mechanism of medium-energy electrons on the closed field line remains to be solved. We also report that a density cavity in the wake is observed not above the strongest magnetic field but in its vicinity.

  7. Electrons on closed field lines of lunar crustal fields in the solar wind wake

    NASA Astrophysics Data System (ADS)

    Nishino, Masaki N.; Saito, Yoshifumi; Tsunakawa, Hideo; Takahashi, Futoshi; Fujimoto, Masaki; Harada, Yuki; Yokota, Shoichiro; Matsushima, Masaki; Shibuya, Hidetoshi; Shimizu, Hisayoshi

    2015-04-01

    Plasma signature around crustal magnetic fields is one of the most important topics of the lunar plasma sciences. Although recent spacecraft measurements are revealing solar-wind interaction with the lunar crustal fields on the dayside, plasma signatures around crustal fields on the night side have not been fully studied yet. Here we show evidence of plasma trapping on the closed field lines of the lunar crustal fields in the solar-wind wake, using SELENE (Kaguya) plasma and magnetic field data obtained at 14-15 km altitude from the lunar surface. In contrast to expectation on plasma cavity formation at the strong crustal fields, electron flux is enhanced above Crisium Antipode (CA) anomaly which is one of the strongest lunar crustal fields. The enhanced electron fluxes above CA are characterised by (1) occasional bi-directional field-aligned beams in the lower energy range (< 150 eV) and (2) a medium energy component (150-300 eV) that has a double loss-cone distribution representing bounce motion between the two footprints of the crustal magnetic fields. The low-energy electrons on the closed field lines may come from the lunar night side surface, while supply mechanism of medium-energy electrons on the closed field line remains to be solved. We also report that a density cavity in the wake is observed not above the strongest magnetic field but in its vicinity.

  8. Electrons on closed field lines of lunar crustal fields in the solar wind wake

    NASA Astrophysics Data System (ADS)

    Nishino, M. N.; Saito, Y.; Tsunakawa, H.; Takahashi, F.; Fujimoto, M.; Yokota, S.; Harada, Y.; Matsushima, M.; Shibuya, H.; Shimizu, H.

    2014-12-01

    Plasma signature around crustal magnetic fields is one of the most important topics of the lunar plasma sciences. Although recent spacecraft measurements are revealing solar-wind interaction with the lunar crustal fields on the dayside, plasma signatures around crustal fields on the night side have not been fully studied yet. Here we show evidence of plasma trapping on the closed field lines of the lunar crustal fields in the solar-wind wake, using SELENE (Kaguya) plasma and magnetic field data obtained at 14-15 km altitude from the lunar surface. In contrast to expectation on plasma cavity formation at the strong crustal fields, electron flux is enhanced over Crisium Antipode (CA) anomaly which is one of the strongest lunar crustal fields. The enhanced electron fluxes over the CA anomaly are characterised by (1) occasional bi-directional field-aligned beams in the lower energy range (< 150 eV) and (2) a medium energy component (150-300 eV) that has a double loss-cone distribution that represents bounce motion between the two footprints of the crustal magnetic fields. The low-energy electrons on the closed field lines may come from the lunar night side surface, while supply mechanism of medium-energy electrons on the closed field line remains to be solved. We also report that a density cavity in the wake is observed not above the strongest magnetic field but in its vicinity.

  9. Mean wind field in the urban atmospheric boundary layer by sodar data

    NASA Astrophysics Data System (ADS)

    Yushkov, V. P.

    2008-05-01

    Two-year uninterrupted sodar measurements of vertical profiles of wind speed and direction in the height range 40 to 250-500 m were carried out in two points of Moscow megalopolis. Seasonal and diurnal courses of mean speed profiles, wind speed distributions, wind roses and occurrence of strong and weak wind speed events are shown. Influence of urban heat island and orography on wind field is discussed.

  10. DRUG MARKET RECONSTITUTION AFTER HURRICANE KATRINA: LESSONS FOR LOCAL DRUG ABUSE CONTROL INITIATIVES

    PubMed Central

    Bennett, Alex S.; Golub, Andrew; Dunlap, Eloise

    2011-01-01

    Hurricane Katrina accomplished what no law enforcement initiative could ever achieve: It completely eradicated the New Orleans drug market. However, Katrina did little to eliminate the demand for drugs. This article documents the process of the drug market reconstitution that occurred 2005–2008 based on in-depth interviews and focus groups with predominately low-income drug users and sellers. Before Katrina, the drug market was largely characterized by socially-bonded participants involved with corporate style distribution. After Katrina, a violent freelance market emerged. The conclusion draws recommendations for law enforcement for dealing with drug markets after a major disaster. This article uses New Orleans as a case study to chart the process of drug market reconstitution following an extreme disaster, namely Hurricane Katrina. On August 29, 2005, Hurricane Katrina made landfall and engulfed the New Orleans area, overwhelming levees and causing extensive flooding and destruction across the city. The storm generated 30- to 40-foot waves, which demolished many cities and small towns in Southern Mississippi and Alabama and caused considerable wind damage further inland. Although the hurricane eye missed central New Orleans by about 30 miles, the wave action in Lake Pontchartrain caused several levees to break and flood most of eastern New Orleans, which was under sea level. The storm had an impact on practically all New Orleans residents and almost destroyed New Orleans (Cooper & Block, 2006; Levitt & Whitaker, 2009; Lee, 2006). Our research focused on the impact of this storm on the drug markets in New Orleans. Katrina destroyed the physical environment and organizational structure that sustained the drug trade, yet drug use and sales did not disappear. During and soon after the storm, improvised sales and distribution organizations provided a wide range of illicit drugs to users (see Dunlap, Johnson, Kotarba, & Fackler, 2009; Dunlap & Golub, 2010; Dunlap

  11. Measurement of two-dimensional Doppler wind fields using a field widened Michelson interferometer.

    PubMed

    Langille, Jeffery A; Ward, William E; Scott, Alan; Arsenault, Dennis L

    2013-03-10

    An implementation of the field widened Michelson concept has been applied to obtain high resolution two-dimensional (2D) images of low velocity (<50 m/s) Doppler wind fields in the lab. Procedures and techniques have been developed that allow Doppler wind and irradiance measurements to be determined on a bin by bin basis with an accuracy of less than 2.5 m/s from CCD images over the observed field of view. The interferometer scanning mirror position is controlled to subangstrom precision with subnanometer repeatability using the multi-application low-voltage piezoelectric instrument control electronics developed by COM DEV Ltd.; it is the first implementation of this system as a phase stepping Michelson. In this paper the calibration and characterization of the Doppler imaging system is described and the planned implementation of this new technique for imaging 2D wind and irradiance fields using the earth's airglow is introduced. Observations of Doppler winds produced by a rotating wheel are reported and shown to be of sufficient precision for buoyancy wave observations in airglow in the mesopause region of the terrestrial atmosphere. PMID:23478764

  12. Variance Anisotropy of Solar Wind Velocity and Magnetic Field Fluctuations

    NASA Astrophysics Data System (ADS)

    Oughton, S.; Matthaeus, W. H.; Wan, M.

    2015-12-01

    At MHD scales in the solar wind, velocity and magnetic fieldfluctuations are typically observed to have much more energy in thecomponents transverse to the mean magnetic field, relative to theparallel components [eg, 1,2]. This is often referred to asvariance anisotropy. Various explanations for it have been suggested,including that the fluctuations are predominantly shear Alfvén waves[1] and that turbulent dynamics leads to such states [eg, 3].Here we investigate the origin and strength of such varianceanisotropies, using spectral method simulations of thecompressible (polytropic) 3D MHD equations. We report on results from runs with several different classes ofinitial conditions. These classes include(i) fluctuations polarized only in the same sense as shear Alfvénwaves (aka toroidal polarization),(ii) randomly polarized fluctuations, and(iii) fluctuations restricted so that most of the energy is inmodes which have their wavevectors perpendicular, or nearly so, to thebackground magnetic field: quasi-2D modes. The plasma beta and Mach number dependence [4] of quantities like the variance anisotropy, Alfven ratio, and fraction of the energy in the toroidal fluctuations will be examined, along with the timescales for the development of any systematic features.Implications for solar wind fluctuations will be discussed. References:[1] Belcher & Davis 1971, J. Geophys. Res, 76, 3534.[2] Oughton et al 2015, Phil Trans Roy Soc A, 373, 20140152.[3] Matthaeus et al 1996, J. Geophys. Res, 101, 7619.[4] Smith et al 2006, J. Geophys. Res, 111, A09111.

  13. Observation of high-resolution wind fields and offshore wind turbine wakes using TerraSAR-X imagery

    NASA Astrophysics Data System (ADS)

    Gies, Tobias; Jacobsen, Sven; Lehner, Susanne; Pleskachevsky, Andrey

    2014-05-01

    1. Introduction Numerous large-scale offshore wind farms have been built in European waters and play an important role in providing renewable energy. Therefore, knowledge of behavior of wakes, induced by large wind turbines and their impact on wind power output is important. The spatial variation of offshore wind turbine wake is very complex, depending on wind speed, wind direction, ambient atmospheric turbulence and atmospheric stability. In this study we demonstrate the application of X-band TerraSAR-X (TS-X) data with high spatial resolution for studies on wind turbine wakes in the near and far field of the offshore wind farm Alpha Ventus, located in the North Sea. Two cases which different weather conditions and different wake pattern as observed in the TS-X image are presented. 2. Methods The space-borne synthetic aperture radar (SAR) is a unique sensor that provides two-dimensional information on the ocean surface. Due to their high resolution, daylight and weather independency and global coverage, SARs are particularly suitable for many ocean and coastal applications. SAR images reveal wind variations on small scales and thus represent a valuable means in detailed wind-field analysis. The general principle of imaging turbine wakes is that the reduced wind speed downstream of offshore wind farms modulates the sea surface roughness, which in turn changes the Normalized Radar Cross Section (NRCS, denoted by σ0) in the SAR image and makes the wake visible. In this study we present two cases at the offshore wind farm Alpha Ventus to investigate turbine-induced wakes and the retrieved sea surface wind field. Using the wind streaks, visible in the TS-X image and the shadow behind the offshore wind farm, induced by turbine wake, the sea surface wind direction is derived and subsequently the sea surface wind speed is calculated using the latest generation of wind field algorithm XMOD2. 3. Case study alpha ventus Alpha Ventus is located approximately 45 km from the

  14. Sediment from Hurricane Katrina: Potential to Produce Pulmonary Dysfunction in Mice

    PubMed Central

    Wang, Kai; You, Dahui; Balakrishna, Shrilatha; Ripple, Michael; Ahlert, Terry; Fahmy, Baher; Becnel, David; Daly, Melissa; Subra, Wilma; McElduff, James S.; Lomax, Larry G.; Troxclair, Dana; Cormier, Stephania A.

    2008-01-01

    On August 29, 2005, Hurricane Katrina made landfall along the Gulf Coast as a Category 3 hurricane. The associated storm surge and heavy rainfall resulted in major flooding throughout the New Orleans area. As the flood waters receded, thick sediment was left covering the ground and coating the interior of homes. This sediment was dispersed into the air and inhaled as dust by returning residents and workers. Our objective in this study was to evaluate the potential pulmonary effects associated with the respirable particulate matter (PM) derived from Hurricane Katrina (HK-PM) in mice. Samples of PM were collected from several locations along the Gulf Coast on September 30 and October 2, 2005 and had a mean aerodynamic diameter ranging from 3-5 μm). Chemical analysis and cytotoxicity assays were performed for all HK-PM samples. A few samples with varying levels of cytotoxicity were chosen for an acute inhalation exposure study. Airborne PM10 levels recorded in the New Orleans area post-Katrina were variable, ranging from 70 μg/m3 in Gentilly to 688 μg/m3 in Lakeview (residential areas). Mice exposed to one of these samples developed significant pulmonary inflammation and airways resistance and hyperresponsiveness to methacholine challenge. These studies demonstrate that dispersion of certain Katrina sediment samples through either natural (e.g., wind) or mechanical (e.g., vehicles) processes promotes airflow obstruction in mice. PMID:19079667

  15. Spatial interpolation of fine particulate matter concentrations using the shortest wind-field path distance.

    PubMed

    Li, Longxiang; Gong, Jianhua; Zhou, Jieping

    2014-01-01

    Effective assessments of air-pollution exposure depend on the ability to accurately predict pollutant concentrations at unmonitored locations, which can be achieved through spatial interpolation. However, most interpolation approaches currently in use are based on the Euclidean distance, which cannot account for the complex nonlinear features displayed by air-pollution distributions in the wind-field. In this study, an interpolation method based on the shortest path distance is developed to characterize the impact of complex urban wind-field on the distribution of the particulate matter concentration. In this method, the wind-field is incorporated by first interpolating the observed wind-field from a meteorological-station network, then using this continuous wind-field to construct a cost surface based on Gaussian dispersion model and calculating the shortest wind-field path distances between locations, and finally replacing the Euclidean distances typically used in Inverse Distance Weighting (IDW) with the shortest wind-field path distances. This proposed methodology is used to generate daily and hourly estimation surfaces for the particulate matter concentration in the urban area of Beijing in May 2013. This study demonstrates that wind-fields can be incorporated into an interpolation framework using the shortest wind-field path distance, which leads to a remarkable improvement in both the prediction accuracy and the visual reproduction of the wind-flow effect, both of which are of great importance for the assessment of the effects of pollutants on human health. PMID:24798197

  16. Spatial Interpolation of Fine Particulate Matter Concentrations Using the Shortest Wind-Field Path Distance

    PubMed Central

    Li, Longxiang; Gong, Jianhua; Zhou, Jieping

    2014-01-01

    Effective assessments of air-pollution exposure depend on the ability to accurately predict pollutant concentrations at unmonitored locations, which can be achieved through spatial interpolation. However, most interpolation approaches currently in use are based on the Euclidean distance, which cannot account for the complex nonlinear features displayed by air-pollution distributions in the wind-field. In this study, an interpolation method based on the shortest path distance is developed to characterize the impact of complex urban wind-field on the distribution of the particulate matter concentration. In this method, the wind-field is incorporated by first interpolating the observed wind-field from a meteorological-station network, then using this continuous wind-field to construct a cost surface based on Gaussian dispersion model and calculating the shortest wind-field path distances between locations, and finally replacing the Euclidean distances typically used in Inverse Distance Weighting (IDW) with the shortest wind-field path distances. This proposed methodology is used to generate daily and hourly estimation surfaces for the particulate matter concentration in the urban area of Beijing in May 2013. This study demonstrates that wind-fields can be incorporated into an interpolation framework using the shortest wind-field path distance, which leads to a remarkable improvement in both the prediction accuracy and the visual reproduction of the wind-flow effect, both of which are of great importance for the assessment of the effects of pollutants on human health. PMID:24798197

  17. Three Dimensional Dynamic Model Based Wind Field Reconstruction from Lidar Data

    NASA Astrophysics Data System (ADS)

    Raach, Steffen; Schlipf, David; Haizmann, Florian; Cheng, Po Wen

    2014-06-01

    Using the inflowing horizontal and vertical wind shears for individual pitch controller is a promising method if blade bending measurements are not available. Due to the limited information provided by a lidar system the reconstruction of shears in real-time is a challenging task especially for the horizontal shear in the presence of changing wind direction. The internal model principle has shown to be a promising approach to estimate the shears and directions in 10 minutes averages with real measurement data. The static model based wind vector field reconstruction is extended in this work taking into account a dynamic reconstruction model based on Taylor's Frozen Turbulence Hypothesis. The presented method provides time series over several seconds of the wind speed, shears and direction, which can be directly used in advanced optimal preview control. Therefore, this work is an important step towards the application of preview individual blade pitch control under realistic wind conditions. The method is tested using a turbulent wind field and a detailed lidar simulator. For the simulation, the turbulent wind field structure is flowing towards the lidar system and is continuously misaligned with respect to the horizontal axis of the wind turbine. Taylor's Frozen Turbulence Hypothesis is taken into account to model the wind evolution. For the reconstruction, the structure is discretized into several stages where each stage is reduced to an effective wind speed, superposed with a linear horizontal and vertical wind shear. Previous lidar measurements are shifted using again Taylor's Hypothesis. The wind field reconstruction problem is then formulated as a nonlinear optimization problem, which minimizes the residual between the assumed wind model and the lidar measurements to obtain the misalignment angle and the effective wind speed and the wind shears for each stage. This method shows good results in reconstructing the wind characteristics of a three dimensional

  18. Observations of oceanic surface-wind fields from the Nimbus-7 microwave radiometer

    NASA Technical Reports Server (NTRS)

    Miller, J. R.; Geyser, J. E.; Chang, A. T. C.; Wilheit, T. T., Jr.

    1982-01-01

    Brightness temperatures from the five-frequency dual-polarized scanning multichannel microwave radiometer (SMMR) on Nimbus 7 have been used to obtain surface wind fields over the ocean. The satellite-derived wind field for 1200Z, Feb. 19, 1979, in the eastern North Pacific has been compared with an operationally generated surface-wind analysis field. Previous point comparisons at selected locations have indicated that satellite winds are accurate to 3 m/sec. The results, although of a preliminary nature, indicate that SMMR-derived winds may be used to determine large-scale wind fields over the ocean, particularly in areas of strong wind gradients such as found in cyclonic systems.

  19. A review of wind field models for atmospheric transport

    SciTech Connect

    Ramsdell, J.V. Jr.; Skyllingstad, E.D.

    1993-06-01

    The primary objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emissions since 1944 from the US Department of Energy`s (DOE) Hanford Site near Richland, Washington. The HEDR Project is developing a computer code to estimate these doses and their uncertainties. The code, known as the HEDR integrated Code (HEDRIC), consists of four separate component codes. One of the component codes, called the Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) combines meteorological and release data to estimate time-integrated air concentrations and surface contamination at specific locations in the vicinity of the Hanford Site. The RATCHET domain covers approximately 75,000 square miles, extending from the crest of the Cascade Mountains on the west to the eastern edge of the Idaho panhandle and from central Oregon on the south to the Canadian border. This letter report explains the procedures in RATCHET that transform observed wind data into the wind fields used in atmospheric transport calculations. It also describes and evaluates alternative procedures not selected for use in RATCHET.

  20. Design development and construction of the RFX field shaping winding

    SciTech Connect

    Chitarin, G.; Guarnieri, M.; Stella, A.

    1989-03-01

    The paper describes the development work on the design and the manufacture of the RFX Field Shaping Winding, from the preliminary analysis and the tests on prototypes to the final design. The winding consists of 16 coils, with 24 copper turns each and of diameters up to 5.5 m. The maximum current is 6.25 kA and the maximum voltage to earth is 35 kV. Each coil is supported in 24 radial locations and the electrodynamic load on a single coil is approximately 40 kN/m in normal operation. Fiberglass impregnated with epoxy resin, reinforced in places with polymide tape, has been used for the insulation. The high levels of the electrical and mechanical strength specified present conflicting constraints, which have required some care in the structural design and the definition of insulation system and impregnation technology. Although the use of copper coils with this kid of insulation may seem obvious and well established, indeed the stringent operational requirements have posed a number of problems which have demanded extensive work on the design and prototype development.

  1. Exploring the nearshore marine wind profile from field measurements and numerical hindcast

    NASA Astrophysics Data System (ADS)

    del Jesus, F.; Menendez, M.; Guanche, R.; Losada, I.

    2012-12-01

    Wind power is the predominant offshore renewable energy resource. In the last years, offshore wind farms have become a technically feasible source of electrical power. The economic feasibility of offshore wind farms depends on the quality of the offshore wind conditions compared to that of onshore sites. Installation and maintenance costs must be balanced with more hours and a higher quality of the available resources. European offshore wind development has revealed that the optimum offshore sites are those in which the distance from the coast is limited with high available resource. Due to the growth in the height of the turbines and the complexity of the coast, with interactions between inland wind/coastal orography and ocean winds, there is a need for field measurements and validation of numerical models to understand the marine wind profile near the coast. Moreover, recent studies have pointed out that the logarithmic law describing the vertical wind profile presents limitations. The aim of this work is to characterize the nearshore vertical wind profile in the medium atmosphere boundary layer. Instrumental observations analyzed in this work come from the Idermar project (www.Idermar.es). Three floating masts deployed at different locations on the Cantabrian coast provide wind measurements from a height of 20 to 90 meters. Wind speed and direction are measured as well as several meteorological variables at different heights of the profile. The shortest wind time series has over one year of data. A 20 year high-resolution atmospheric hindcast, using the WRF-ARW model and focusing on hourly offshore wind fields, is also analyzed. Two datasets have been evaluated: a European reanalysis with a ~15 Km spatial resolution, and a hybrid downscaling of wind fields with a spatial resolution of one nautical mile over the northern coast of Spain.. These numerical hindcasts have been validated based on field measurement data. Several parameterizations of the vertical wind

  2. Conversion of magnetic field energy into kinetic energy in the solar wind

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.

    1972-01-01

    The outflow of the solar magnetic field energy (the radial component of the Poynting vector) per steradian is inversely proportional to the solar wind velocity. It is a decreasing function of the heliocentric distance. When the magnetic field effect is included in the one-fluid model of the solar wind, the transformation of magnetic field energy into kinetic energy during the expansion process increases the solar wind velocity at 1 AU by 17 percent.

  3. Two-component wind fields from single scanning aerosol lidar

    NASA Astrophysics Data System (ADS)

    Mayor, Shane D.; Derian, Pierre; Mauzey, Christopher F.; Hamada, Masaki

    2015-09-01

    An overview of recent research results on the performance of two motion estimation algorithms used to deduce two-component horizontal wind fields from ground-based scanning elastic backscatter lidar is presented. One motion estimation algorithm is a traditional cross-correlation method optimized for atmospheric lidar data. The second algorithm is a recently-developed wavelet-based optical flow. An intercomparison of experimental results with measurements from an independent Doppler lidar over an agricultural area in Chico, California, during daytime convective conditions in 2013-14 are presented. Finally, early results from application of the algorithms to data collected over the ocean from a compact and portable aerosol lidar that was deployed on the northern California coast in March of 2015 are presented.

  4. Magnetic fields at the solar wind termination shock.

    PubMed

    Burlaga, L F; Ness, N F; Acuña, M H; Lepping, R P; Connerney, J E P; Richardson, J D

    2008-07-01

    A transition between the supersonic solar wind and the subsonic heliosheath was observed by Voyager 1, but the expected termination shock was not seen owing to a gap in the telemetry. Here we report observations of the magnetic field structure and dynamics of the termination shock, made by Voyager 2 on 31 August-1 September 2007 at a distance of 83.7 au from the Sun (1 au is the Earth-Sun distance). A single crossing of the shock was expected, with a boundary that was stable on a timescale of several days. But the data reveal a complex, rippled, quasi-perpendicular supercritical magnetohydrodynamic shock of moderate strength undergoing reformation on a scale of a few hours. The observed structure suggests the importance of ionized interstellar atoms ('pickup protons') at the shock. PMID:18596803

  5. Magnetic Fields in the Termination Shock, Heliosheath and Solar Wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    2008-01-01

    This paper will discuss recent magnetic field observations of the termination shock (TS), heliosheath (HSH), and supersonic solar wind (SW) made by Voyager 1 (V1) and Voyager 2 (V2). Voyager 2 crossed the TS at least 5 times at 83.7 AU and 27.5deg South heliographic latitude during 2007/242.14 to 244.80. The structure of the shock, observed on three of the crossings, was highly variable, ranging from a simple quasi-perpendicular supercritical shock to a complex profile suggesting reformation. Two merged interaction regions were observed in the SW upstream of the TS, and the magnetic field increased to relatively high values during the month prior to crossing the TS. Voyager 2 observations in the HSH will also be discussed. Voyager 1 observed a small radial gradient of the magnetic field strength B in the HSH. It is expected that B should increase from the TS to heliopause, but the available predictions of the profile are not adequate to compare with the observations. Voyager 1 has entered a unipolar region, as the heliospheric current sheet moved below the latitude of V1.

  6. Using ground-based stereo cameras to derive cloud-level wind fields.

    PubMed

    Porter, John N; Cao, Guang Xia

    2009-08-15

    Upper-level wind fields are obtained by tracking the motion of cloud features as seen in calibrated ground-based stereo cameras. By tracking many cloud features, it is possible to obtain horizontal wind speed and direction over a cone area throughout the troposphere. Preliminary measurements were made at the Mauna Loa Observatory, and resulting wind measurements are compared with winds from the Hilo, Hawaii radiosondes. PMID:19684790

  7. Combined Experiment Phase 1. [Horizontal axis wind turbines: wind tunnel testing versus field testing

    SciTech Connect

    Butterfield, C.P.; Musial, W.P.; Simms, D.A.

    1992-10-01

    How does wind tunnel airfoil data differ from the airfoil performance on an operating horizontal axis wind turbine (HAWT) The National Renewable Energy laboratory has been conducting a comprehensive test program focused on answering this question and understanding the basic fluid mechanics of rotating HAWT stall aerodynamics. The basic approach was to instrument a wind rotor, using an airfoil that was well documented by wind tunnel tests, and measure operating pressure distributions on the rotating blade. Based an the integrated values of the pressure data, airfoil performance coefficients were obtained, and comparisons were made between the rotating data and the wind tunnel data. Care was taken to the aerodynamic and geometric differences between the rotating and the wind tunnel models. This is the first of two reports describing the Combined Experiment Program and its results. This Phase I report covers background information such as test setup and instrumentation. It also includes wind tunnel test results and roughness testing.

  8. CFD wind tunnel test: Field velocity patterns of wind on a building with a refuge floor

    NASA Astrophysics Data System (ADS)

    Cheng, C. K.; Yuen, K. K.; Lam, K. M.; Lo, S. M.

    2005-10-01

    This paper reports a CFD wind tunnel study of wind patterns on a square-plan building with a refuge floor at its mid-height level. In this study, a technique of using calibrated power law equations of velocity and turbulent intensity applied as the boundary conditions in CFD wind tunnel test is being evaluated by the physical wind tunnel data obtained by the Principal Author with wind blowing perpendicularly on the building without a refuge floor. From the evaluated results, an optimised domain of flow required to produce qualitative agreement between the wind tunnel data and simulated results is proposed in this paper. Simulated results with the evaluated technique are validated by the wind tunnel data obtained by the Principal Author. The results contribute to an understanding of the fundamental behaviour of wind flow in a refuge floor when wind is blowing perpendicularly on the building. Moreover, the results reveal that the designed natural ventilation of a refuge floor may not perform desirably when the wind speed on the level is low. Under this situation, the refuge floor may become unsafe if smoke was dispersed in the leeward side of the building at a level immediately below the refuge floor.

  9. Real-Time Teaching: Lessons from Katrina

    ERIC Educational Resources Information Center

    Phillips, Antoinette S.; Phillips, Carl R.

    2008-01-01

    Professors strive constantly to find ways for students to apply what they are learning in the classroom, thereby reinforcing principles being taught and increasing student interest and involvement in the learning process. Hurricane Katrina's devastating impact on the Gulf Coast had wide-ranging consequences. As a result, many individuals…

  10. Educators Reach out to Katrina Victims

    ERIC Educational Resources Information Center

    Hardy, Lawrence

    2006-01-01

    The emotional trauma of recent events may never go away. A million people were uprooted by Hurricane Katrina, including an estimated 372,000 children of school age. Three weeks later, Hurricane Rita slammed into the Texas-Louisiana coastline, forcing thousands more to evacuate. Acute symptoms of trauma range from confusion, nightmares, and…

  11. Revisiting the Gulf Coast after Katrina

    ERIC Educational Resources Information Center

    Principal, 2009

    2009-01-01

    In August 2005, the world witnessed one of the most destructive natural disasters on America's mainland. Hurricane Katrina, followed a month later by Hurricane Rita, brought more than broken levees, flooded streets and homes, and destroyed businesses. It caused changes in the dynamics and the demographic and cultural makeup of the region. One of…

  12. Katrina Effect on Mathematics Achievement in Mississippi

    ERIC Educational Resources Information Center

    Lamb, John; Lewis, Mark; Gross, Sarah

    2013-01-01

    Hurricane Katrina caused severe physical damage to the Gulf Coast states of Louisiana, Mississippi, and Alabama. Homes and businesses were destroyed. Natural habitats were annihilated, and many Americans were displaced for days, weeks, and even years. This study investigated the within-subject effects and contrasts of poverty, rurality, and…

  13. SSC marks anniversary of Hurricane Katrina

    NASA Technical Reports Server (NTRS)

    2006-01-01

    At the Hurricane Katrina observance held Aug. 29 in the StenniSphere auditorium, Stennis Space Center Deputy Director David Throckmorton (left) and RAdm. Timothy McGee, Commander, Naval Meteorology and Oceanography Command, unveil a plaque dedicated to SSC employees.

  14. Rebuilding New Orleans Schools after Katrina

    ERIC Educational Resources Information Center

    Vail, Kathleen

    2006-01-01

    In this article, the author talks about the rebuilding of the public school system in New Orleans after Hurricane Katrina. A group of local and state educators, community leaders, and business people, headed by Tulane University President Scott Cowen, recommended that New Orleans become a hybrid of traditional public schools and charter schools,…

  15. Schooling the Forgotten Kids of Hurricane Katrina

    ERIC Educational Resources Information Center

    Cook, Glenn

    2006-01-01

    In this article, the author talks about students being taking in public schools in Houston and Dallas, as well as other states, after evacuating from New Orleans which was struck by Hurricane Katrina and Hurricane Rita. For students displaced by the storm, mobility is as constant as stability is elusive. Already traumatized and faced with the loss…

  16. The economics and ethics of Hurricane Katrina.

    PubMed

    Rockwell, Llewellyn H; Block, Walter E

    2010-01-01

    How might free enterprise have dealt with Hurricane Katrina and her aftermath. This article probes this question at increasing levels of radicalization, starting with the privatization of several government “services” and ending with the privatization of all of them. PMID:20939132

  17. Assessing Hurricane Katrina Damage to the Mississippi Gulf Coast Using IKONOS Imagery

    NASA Technical Reports Server (NTRS)

    Spruce, Joseph P.; McKellip, Rodney

    2007-01-01

    Hurricane Katrina hit southwestern Mississippi on August 29, 2005, at 10 a.m. CDT as a category 3 event with storm surges up to approximately 9 m and sustained winds of approximately 120 mph. The hurricane ravaged several coastal towns, destroying or severely damaging hundreds of homes. Hurricand Katrina deposited millions of tons of debris and caused severe damage to coastal forests. In response, several Federal agencies have been using a broad range of remotely sensed data (e.g., IKONOS) to aid damage assessment and disaster recovery efforts. This presentation discusses an effort to use IKONOS data for damage assessment, based on data collected over southwestern coastal Mississippi on September 2, 2005.

  18. Dune field pattern formation and recent transporting winds in the Olympia Undae Dune Field, north polar region of Mars

    NASA Astrophysics Data System (ADS)

    Ewing, Ryan C.; Peyret, Aymeric-Pierre B.; Kocurek, Gary; Bourke, Mary

    2010-08-01

    High-Resolution Imaging Science Experiment (HiRISE) imagery of the central Olympia Undae Dune Field in the north polar region of Mars shows a reticulate dune pattern consisting of two sets of nearly orthogonal dune crestlines, with apparent slipfaces on the primary crests, ubiquitous wind ripples, areas of coarse-grained wind ripples, and deflated interdune areas. Geomorphic evidence and dune field pattern analysis of dune crest length, spacing, defect density, and orientation indicates that the pattern is complex, representing two constructional generations of dunes. The oldest and best-organized generation forms the primary crestlines and is transverse to circumpolar easterly winds. Gross bed form-normal analysis of the younger pattern of crestlines indicates that it emerged with both circumpolar easterly winds and NE winds and is reworking the older pattern. Mapping of secondary flow fields over the dunes indicates that the most recent transporting winds were from the NE. The younger pattern appears to represent an influx of sediment to the dune field associated with the development of the Olympia Cavi reentrant, with NE katabatic winds channeling through the reentrant. A model of the pattern reformation based upon the reconstructed primary winds and resulting secondary flow fields shows that the development of the secondary pattern is controlled by the boundary condition of the older dune topography.

  19. Numerical simulations of flow fields through conventionally controlled wind turbines & wind farms

    NASA Astrophysics Data System (ADS)

    Emre Yilmaz, Ali; Meyers, Johan

    2014-06-01

    In the current study, an Actuator-Line Model (ALM) is implemented in our in-house pseudo-spectral LES solver SP-WIND, including a turbine controller. Below rated wind speed, turbines are controlled by a standard-torque-controller aiming at maximum power extraction from the wind. Above rated wind speed, the extracted power is limited by a blade pitch controller which is based on a proportional-integral type control algorithm. This model is used to perform a series of single turbine and wind farm simulations using the NREL 5MW turbine. First of all, we focus on below-rated wind speed, and investigate the effect of the farm layout on the controller calibration curves. These calibration curves are expressed in terms of nondimensional torque and rotational speed, using the mean turbine-disk velocity as reference. We show that this normalization leads to calibration curves that are independent of wind speed, but the calibration curves do depend on the farm layout, in particular for tightly spaced farms. Compared to turbines in a lone-standing set-up, turbines in a farm experience a different wind distribution over the rotor due to the farm boundary-layer interaction. We demonstrate this for fully developed wind-farm boundary layers with aligned turbine arrangements at different spacings (5D, 7D, 9D). Further we also compare calibration curves obtained from full farm simulations with calibration curves that can be obtained at a much lower cost using a minimal flow unit.

  20. Line-Driven Winds in Strong Gravitational Fields

    NASA Astrophysics Data System (ADS)

    Dorodnitsyn, Anton

    A general physical mechanism which could contribute to the formation of fast line-driven outflows at the vicinity of strong gravitational field sources is proposed. The problem of the acceleration of a wind due to absorption of the radiation flux in lines is considered at the vicinity of a supermassive BH. We argue that the gradient of the gravitational potential plays the same role as the velocity gradient plays in Sobolev approximation. Both Doppler effect and gravitational redshifting are taken into account in Sobolev approximation. It is shown that the radiation force becomes a function of the local velocity gradient and the gradient of the gravitational potential. The derived equation of motion has a critical point that is different from that of Castor Abbott Klein (CAK). A solution that is continuous through the singular point is obtained numerically. A comparison with CAK theory is presented. It is shown that the developed theory predicts terminal velocities which are greater than those obtained from the CAK theory. Applications to the problem of the formation of fast outflows from AGN are discussed.

  1. The large-scale magnetic field in the solar wind. [astronomical models of interplanetary magnetics and the solar magnetic field

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Ness, N. F.

    1976-01-01

    A literature review is presented of theoretical models of the interaction of the solar wind and interplanetary magnetic fields. Observations of interplanetary magnetic fields by the IMP and OSO spacecraft are discussed. The causes for cosmic ray variations (Forbush decreases) by the solar wind are examined. The model of Parker is emphasized. This model shows the three dimensional magnetic field lines of the solar wind to have the form of spirals wrapped on cones. It is concluded that an out-of-the-ecliptic solar probe mission would allow the testing and verification of the various theoretical models examined. Diagrams of the various models are shown.

  2. Global measurements of wind fields using the Laser Atmospheric Wind Sounder (LAWS) on the Earth Observing System (EOS)

    NASA Technical Reports Server (NTRS)

    Fitzjarrald, Daniel E.

    1988-01-01

    The technology for measuring global wind fields in space by the Laser Atmospheric Wind Sounder (LAWS) to be flown on the Earth Observing System (EOS) is discussed. Studies initiated by NASA to determine the feasibility of using Doppler lidar from a platform in space to measure the wind globally have shown the general feasibility of the technique and have identified the technological problems that need to be resolved. Among the lidar systems being evaluated, CO2 coherent detection lidar is given special consideration. A comprehensive research program, the Global Backscatter Experiment, has been established to study global distribution of naturally occurring atmospheric aerosols that provide signal return at the wavelengths used by the techniques under consideration. Wind profiles from space will provide essential information for advancing the skill of numerical weather prediction, furthering the present knowledge of the large-scale atmospheric circulation and climate dynamics, and of global biogeochemical and hydrologic cycles.

  3. Fields of Opportunity: Wind Machines Return to the Plains

    ERIC Educational Resources Information Center

    Sowers, Jacob

    2006-01-01

    The last two decades have seen a rebirth of wind machines on the rural landscape. In ironic fashion the wind's kinetic energy has grown in significance through its ability to generate commercial amounts of electricity, the commodity that a few generations earlier hastened the demise of the old Great Plains windmill. Yet the reemergence of wind…

  4. Examination of forced unsteady separated flow fields on a rotating wind turbine blade

    SciTech Connect

    Huyer, S. )

    1993-04-01

    The wind turbine industry faces many problems regarding the construction of efficient and predictable wind turbine machines. Steady state, two-dimensional wind tunnel data are generally used to predict aerodynamic loads on wind turbine blades. Preliminary experimental evidence indicates that some of the underlying fluid dynamic phenomena could be attributed to dynamic stall, or more specifically to generation of forced unsteady separated flow fields. A collaborative research effort between the University of Colorado and the National Renewable Energy Laboratory was conducted to systematically categorize the local and global effects of three- dimensional forced unsteady flow fields.

  5. Joint Offshore Wind Field Monitoring with Spaceborne SAR and Platform-Based Doppler LIDAR Measurements

    NASA Astrophysics Data System (ADS)

    Jacobsen, S.; Lehner, S.; Hieronimus, J.; Schneemann, J.; Kuhn, M.

    2015-04-01

    The increasing demand for renewable energy resources has promoted the construction of offshore wind farms e.g. in the North Sea. While the wind farm layout consists of an array of large turbines, the interrelation of wind turbine wakes with the remaining array is of substantial interest. The downstream spatial evolution of turbulent wind turbine wakes is very complex and depends on manifold parameters such as wind speed, wind direction and ambient atmospheric stability conditions. To complement and validate existing numerical models, corresponding observations are needed. While in-situ measurements with e.g. anemometers provide a time-series at the given location, the merits of ground-based and space- or airborne remote sensing techniques are indisputable in terms of spatial coverage. Active microwave devices, such as Scatterometer and Synthetic Aperture Radar (SAR), have proven their capabilities of providing sea surface wind measurements and particularly SAR images reveal wind variations at a high spatial resolution while retaining the large coverage area. Platform-based Doppler LiDAR can resolve wind fields with a high spatial coverage and repetition rates of seconds to minutes. In order to study the capabilities of both methods for the investigation of small scale wind field structures, we present a direct comparison of observations obtained by high resolution TerraSAR-X (TS-X) X-band SAR data and platform-based LiDAR devices at the North Sea wind farm alpha ventus. We furthermore compare the results with meteorological data from the COSMO-DE model run by the German Weather Service DWD. Our study indicates that the overall agreement between SAR and LiDAR wind fields is good and that under appropriate conditions small scale wind field variations compare significantly well.

  6. Appendix I1-2 to Wind HUI Initiative 1: Field Campaign Report

    SciTech Connect

    John Zack; Deborah Hanley; Dora Nakafuji

    2012-07-15

    This report is an appendix to the Hawaii WindHUI efforts to dev elop and operationalize short-term wind forecasting and wind ramp event forecasting capabilities. The report summarizes the WindNET field campaign deployment experiences and challenges. As part of the WindNET project on the Big Island of Hawaii, AWS Truepower (AWST) conducted a field campaign to assess the viability of deploying a network of monitoring systems to aid in local wind energy forecasting. The data provided at these monitoring locations, which were strategically placed around the Big Island of Hawaii based upon results from the Oahu Wind Integration and Transmission Study (OWITS) observational targeting study (Figure 1), provided predictive indicators for improving wind forecasts and developing responsive strategies for managing real-time, wind-related system events. The goal of the field campaign was to make measurements from a network of remote monitoring devices to improve 1- to 3-hour look ahead forecasts for wind facilities.

  7. Solar flare acceleration of solar wind - Influence of active region magnetic field

    NASA Technical Reports Server (NTRS)

    Lundstedt, H.; Wilcox, J. M.; Scherrer, P. H.

    1981-01-01

    The direction of the photospheric magnetic field at the site of a solar flare is a good predictor of whether the flare will accelerate solar wind plasma. If the field has a southward component, high-speed solar wind plasma is usually observed near the earth about 4 days later. If the field has a northward component, such high-speed solar wind is almost never observed. Southward-field flares may then be expected to have much larger terrestrial effects than northward flares.

  8. Evaluation of wind fields used in Grand Canyon Visibility Transport Commission analyses.

    PubMed

    Green, M C; Pai, P; Ashbaugh, L; Farber, R J

    2000-05-01

    The Grand Canyon Visibility Transport Commission (GCVTC) was established by the U.S. Congress to assess the potential impacts of projected growth on atmospheric visibility at Grand Canyon National Park and to make recommendations to the U.S. Environmental Protection Agency on what measures could be taken to avoid such adverse impacts. A critical input to the assessment tool used by the commission was three-dimensional model-derived wind fields used to transport the emissions. This paper describes the evaluation of the wind fields used at various stages in the assessment. Wind fields evaluated included those obtained from the Colorado State University Regional Atmospheric Modeling System (RAMS), the National Meteorological Center's Nested Grid Model (NGM), and the National Oceanic and Atmospheric Administration's Atmospheric Transport and Dispersion (ATAD) trajectory model. The model-derived wind fields were evaluated at multiple vertical levels at several locations in the southwestern United States by determining differences between model predicted winds and winds that were measured using radiosonde and radar wind profiler data. Model-derived winds were also evaluated by determining the percent of time that they were within acceptable differences from measured winds. All models had difficulties, generally meeting the acceptable criteria for less than 50% of the predictions. The RAMS model had a persistent bias toward southwesterly winds at the expense of other directions, especially failing to represent channeling by north-south mountain ranges in the lower levels. The NGM model exhibited a substantial bias in the summer months by extending northwesterly winds in the eastern Pacific Ocean well inland, in contrast to the observed southwesterlies at inland locations. The simpler ATAD trajectory model performed somewhat better than the other models, probably because of its use of more upper air sites. The results of the evaluation indicated that these wind fields

  9. Deriving dynamics from GPS radio occultation: Three-dimensional wind fields for monitoring the climate

    PubMed Central

    Scherllin-Pirscher, Barbara; Steiner, Andrea Karin; Kirchengast, Gottfried

    2014-01-01

    Global Positioning System (GPS) radio occultation (RO) measurements are proven highly useful for observing the thermal structure of the troposphere and stratosphere. Here we use RO data for the first time to derive climatological wind fields from sampling error-corrected geopotential height fields on isobaric surfaces from about 800 hPa to 3 hPa. We find monthly mean RO geostrophic wind and gradient wind fields (2007 to 2012, about 500 km horizontal resolution, outside tropics) to clearly capture all main wind features, with differences to atmospheric analysis winds being, in general, smaller than 2 m/s. Larger differences (up to 10 m/s) occur close to the subtropical jet where RO winds underestimate actual winds. Such biases are caused by the geostrophic and gradient wind approximations, while RO retrieval errors introduce negligible effect. These results demonstrate that RO wind fields are of high quality and can provide new information on troposphere-stratosphere dynamics, for the benefit of monitoring the climate from weekly to decadal scales. PMID:26074640

  10. Flooding in the Aftermath of Hurricane Katrina

    NASA Technical Reports Server (NTRS)

    2005-01-01

    These views of the Louisiana and Mississippi regions were acquired before and one day after Katrina made landfall along the Gulf of Mexico coast, and highlight many of the changes to the rivers and vegetation that occurred between the two views. The images were acquired by NASA's Multi-angle Imaging SpectroRadiometer (MISR) on August 14 and August 30, 2005. These multiangular, multispectral false-color composites were created using red band data from MISR's 46o backward and forward-viewing cameras, and near-infrared data from MISR's nadir camera. Such a display causes water bodies and inundated soil to appear in blue and purple hues, and highly vegetated areas to appear bright green. The scene differentiation is a result of both spectral effects (living vegetation is highly reflective at near-infrared wavelengths whereas water is absorbing) and of angular effects (wet surfaces preferentially forward scatter sunlight). The two images were processed identically and extend from the regions of Greenville, Mississippi (upper left) to Mobile Bay, Alabama (lower right).

    There are numerous rivers along the Mississippi coast that were not apparent in the pre-Katrina image; the most dramatic of these is a new inlet in the Pascagoula River that was not apparent before Katrina. The post-Katrina flooding along the edges of Lake Pontchartrain and the city of New Orleans is also apparent. In addition, the agricultural lands along the Mississippi floodplain in the upper left exhibit stronger near-infrared brightness before Katrina. After Katrina, many of these agricultural areas exhibit a stronger signal to MISR's oblique cameras, indicating the presence of inundated soil throughout the floodplain. Note that clouds appear in a different spot for each view angle due to a parallax effect resulting from their height above the surface.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the entire globe between 82o north and 82o

  11. The variability of the surface wind field in the equatorial Pacific Ocean: Criteria for satellite measurements

    NASA Technical Reports Server (NTRS)

    Halpern, D.

    1984-01-01

    The natural variability of the equatorial Pacific surface wind field is described from long period surface wind measurements made at three sites along the equator (95 deg W, 109 deg 30 W, 152 deg 30 W). The data were obtained from surface buoys moored in the deep ocean far from islands or land, and provide criteria to adequately sample the tropical Pacific winds from satellites.

  12. SMART Wind Turbine Rotor: Design and Field Test

    SciTech Connect

    Berg, Jonathan C.; Resor, Brian R.; Paquette, Joshua A.; White, Jonathan R.

    2014-01-29

    This report documents the design, fabrication, and testing of the SMART Rotor. This work established hypothetical approaches for integrating active aerodynamic devices (AADs) into the wind turbine structure and controllers.

  13. Impact of ocean warm layer thickness on the intensity of hurricane Katrina in a regional coupled model

    NASA Astrophysics Data System (ADS)

    Seo, Hyodae; Xie, Shang-Ping

    2013-10-01

    The effect of pre-storm subsurface thermal structure on the intensity of hurricane Katrina (2005) is examined using a regional coupled model. The Estimating Circulation and Climate of Ocean (ECCO) ocean state estimate is used to initialize the ocean component of the coupled model, and the source of deficiencies in the simulation of Katrina intensity is investigated in relation to the initial depth of 26 °C isotherm (D26). The model underestimates the intensity of Katrina partly due to shallow D26 in ECCO. Sensitivity tests with various ECCO initial fields indicate that the correct relationship between intensity and D26 cannot be derived because D26 variability is underestimated in ECCO. A series of idealized experiments is carried out by modifying initial ECCO D26 to match the observed range. A more reasonable relationship between Katrina’s intensity and pre-storm D26 emerges: the intensity is much more sensitive to D26 than to sea surface temperature (SST). Ocean mixed layer process plays a critical role in modulating inner-core SSTs when D26 is deep, reducing mixed layer cooling and lowering the center pressure of the Katrina. Our result lends strong support to the notion that accurate initialization of pre-storm subsurface thermal structure in prediction models is critical for a skillful forecast of intensity of Katrina and likely other intense storms.

  14. Wind Loads on Flat Plate Photovoltaic Array Fields

    NASA Technical Reports Server (NTRS)

    Miller, R.; Zimmerman, D.

    1979-01-01

    The aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays were investigated. Local pressure distributions and total aerodynamic forces on the arrays are shown. Design loads are presented to cover the conditions of array angles relative to the ground from 20 deg to 60 deg, variable array spacings, a ground clearance gap up to 1.2 m (4 ft) and array slant heights of 2.4 m (8 ft) and 4.8 m (16 ft). Several means of alleviating the wind loads on the arrays are detailed. The expected reduction of the steady state wind velocity with the use of fences as a load alleviation device are indicated to be in excess of a factor of three for some conditions. This yields steady state wind load reductions as much as a factor of ten compared to the load incurred if no fence is used to protect the arrays. This steady state wind load reduction is offset by the increase in turbulence due to the fence but still an overall load reduction of 2.5 can be realized. Other load alleviation devices suggested are the installation of air gaps in the arrays, blocking the flow under the arrays and rounding the edges of the array. A wind tunnel test plan to supplement the theoretical study and to evaluate the load alleviation devices is outlined.

  15. The relationship between the magnetic field in the Martian magnetotail and upstream solar wind parameters

    NASA Technical Reports Server (NTRS)

    Rosenbauer, H.; Verigin, M. I.; Kotova, G. A.; Livi, S.; Remizov, A. P.; Riedler, W.; Schwingenschuh, K.; Shutte, N. M.; Slavin, J. A.; Szego, K.

    1994-01-01

    Magnetic field data measured by the MAGMA instrument in the Martian magnetotail lobes are compared with the ram pressure of the upstream solar wind observed by the TAUS instrument in the circular orbits of the Phobos 2 spacecraft. High correlation was found between the magnetic field intensity in the Martian magnetotail lobes and the solar wind ram pressure. From this relationship the average flaring angle of the Martian magnetotail was determined as approximately 13 deg, and the average magnetosonic Mach number was estimated as approximately 5. The observed relationship between the Martian magnetotail magnetic field intensity and the solar wind magnetic field reflects the correlation of the solar wind magnetic field to the ram pressure providing a value of approximately 7 for the average Alfvenic Mach number. The flaring angle obtained for the Martian magnetotail was found to be an intermediate value between the flaring angle of the magnetotail of the Earth and that of Venus at comparable distances.

  16. A simple method to estimate threshold friction velocity of wind erosion in the field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nearly all wind erosion models require the specification of threshold friction velocity (TFV). Yet determining TFV of wind erosion in field conditions is difficult as it depends on both soil characteristics and distribution of vegetation or other roughness elements. While several reliable methods ha...

  17. Hurricane Katrina's Impact on Tulane's Teaching Hospitals

    PubMed Central

    Taylor, Ian L.

    2007-01-01

    On Monday, August 29, 2005 Hurricane Katrina passed east of New Orleans causing minimal damage to Tulane's Medical Center. Later that day, levees that protected the city failed and several feet of water entered the hospitals and school buildings. Emergency generators provided power for 36 hours before running out of fuel. Temperatures in the hospitals soared into the upper 90's and conditions were made intolerable by 100% humidity and backed-up sewage. For several days, faculty, residents, nurses and hospital personnel performed heroically, caring for patients in appalling conditions, hand-ventilating critically ill patients in shifts. Approximately 200 patients, and 1500 additional personnel would be evacuated on Wednesday and Thursday from a makeshift heliport on Tulane's parking garage. Current disaster plans may be inadequate should facilities be inaccessible for months because of damage or contamination. Contingency plans also need to be made should outside disaster relief be markedly delayed as was the case with Katrina. PMID:18528490

  18. Environmental impact of Hurricane Katrina on Lake Pontchartrain: Chapter 7G in Science and the storms-the USGS response to the hurricanes of 2005

    USGS Publications Warehouse

    Heitmuller, Thomas; Perez, Brian C.

    2007-01-01

    Hurricane Katrina slammed the Louisiana-Mississippi Gulf Coast with 135-mi/hour (217-km/hour) winds and up to a 30-ft (9-m) storm surge. Lake Pontchartrain was further subjected to environmental threat by way of the millions of gallons of contaminated flood water that were pumped daily from the city of New Orleans into the lake.

  19. Generating wind fields that honour point observations and physical conservation laws

    NASA Astrophysics Data System (ADS)

    Schlabing, Dirk; Bárdossy, András

    2015-04-01

    Wind exhibits a strong spatial and temporal variability. In the application of lake modelling, these features are important for simulating water flows and stratification correctly, as mean and variance of wind speed determine the input of momentum into the lake. This makes a mere interpolation of point measurements an unsuitable method for producing model input. Additionally to concrete point measurements, more subtle aspects of wind fields are to be reproduced. It follows from the fact that wind vectors represent moving air that a wind field has to be divergency-free in order to be mass-conservative. Further, a temporal sequence of wind fields has to comply with the Navier-Stokes equation in order to conserve momentum. All these constraints can be met by representing the conditioned wind field as a linear combination of unconditioned, normally distributed random fields that individually possess the same spatial covariance structuref as observed wind fields. The aim of having the same covariance structure in the conditioned wind field is formulated as an optimization problem with respect to the weights used in the linear combination. With the help of Quadratic Programming (QP) and exploiting the convexity of the problem, feasible solutions can easily be found. In this QP problem, observations become linear constraints. Conservation laws can be incorporated by introducing control volumes in a similar fashion as they are used in fluid mechanics. Budgets of flows through these control volumes become integral conditions in the QP problem. The applicability of the approach will be shown using an artificial example and real-world data measured on shore and on a moving boat on Lake Constance.

  20. Katrina: macro-ethical issues for engineers.

    PubMed

    Newberry, Byron

    2010-09-01

    Hurricane Katrina was one of the worst disasters in United States history. Failures within New Orleans' engineered hurricane protection system (levees and floodwalls) contributed to the severity of the event and have drawn considerable public attention. In the time since Katrina, forensic investigations have uncovered a range of issues and problems related to the engineering work. In this article, my goal is to distill from these investigations, and the related literature that has accumulated, some overarching macro-ethical issues that are relevant for all engineers. I attempt to frame these issues, using illustrative examples taken from Katrina, in a way that might be of pedagogical use and benefit for engineering educators interested in engaging their students in discussions of engineering ethics, societal impact of engineered systems, engineering design, or related topics. Some of the issues discussed are problems of unanticipated failure modes, faulty assumptions, lack or misuse of information, the importance of resiliency, the effects of time, balancing competing interests, attending to the details of interfaces, the fickleness of risk perception, and how the past constrains the present. PMID:19821060

  1. Solar wind proton reflection by lunar crustal magnetic fields observed at low altitude

    NASA Astrophysics Data System (ADS)

    Nishino, M. N.; Fujimoto, M.; Tsunakawa, H.; Saito, Y.; Yokota, S.; Shibuya, H.; Matsushima, M.; Shimizu, H.; Takahashi, F.

    2012-12-01

    We study interaction between the solar wind flow and lunar crustal magnetic fields observed at lower altitudes by SELENE (Kaguya), predominantly focusing on proton reflection above strong crustal fields. Several studies revealed interaction between the solar wind and the Moon, while detailed observation at low altitude including ion measurements has been hardly reported yet. Previous observations at higher altitude revealed that the solar wind protons are not reflected toward the sun but deflected downstream around the solar wind flow direction. Here we report detailed observations of solar wind proton reflection/deflection observed above South Pole-Aitken (SPA) basin at low altitude (typically, lower than 30 km) and at several solar zenith angles. Above wide crustal fields inside the SPA basin, a large amount of incident solar wind protons are deflected and sometimes reflected to come back sunward; in particular, the sunward proton beams are observed at lower solar zenith angle regions. The reflected/deflected protons at times consist of two (or more-than-two) separate components that have been mirror-reflected at different crustal fields. Our result shows that the mirror reflection of incident protons takes place at the altitude much lower than the spacecraft orbit, and suggests that strong compression of the crustal fields at lower solar zenith angle and at lower altitude by the solar wind dynamic pressure is essential.

  2. Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.

    PubMed

    Crary, F J; Clarke, J T; Dougherty, M K; Hanlon, P G; Hansen, K C; Steinberg, J T; Barraclough, B L; Coates, A J; Gérard, J-C; Grodent, D; Kurth, W S; Mitchell, D G; Rymer, A M; Young, D T

    2005-02-17

    The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere. PMID:15716946

  3. Genesis of Dune Fields Under Unidirectional Wind with Sand Input Flux Control: An Experimental Approach

    NASA Astrophysics Data System (ADS)

    Garcia, A.; Courrech du Pont, S.; Rodriguez, S.; Valance, A.; Narteau, C.; Gao, X.; Lucas, A.

    2015-05-01

    Our experimental studies with control of wind and sediment source will characterize more precisely the different modes of dune formation and long-term evolution, and constrain the physics behind the morphogenesis and dynamics of dunes fields.

  4. Solar Wind Interaction with Lunar Crustal Magnetic Fields: Relation to Albedo Swirls

    NASA Technical Reports Server (NTRS)

    Mitchell, D. L.; Lin, R. P.; Harrison, L.; Halekas, J. S.; Hood, L. L.; Acuna, M. H.; Binder, A. B.

    2000-01-01

    The Magnetometer/Electron Reflectometer onboard Lunar Prospector has observed the solar wind interaction with remanent crustal magnetic fields at altitudes from 20 to 120 km. This interaction may be responsible for the formation of albedo swirls.

  5. In-field use of laser Doppler vibrometer on a wind turbine blade

    SciTech Connect

    Rumsey, M.; Hurtado, J.; Hansche, B.

    1998-12-31

    One of our primary goals was to determine how well a laser Doppler vibrometer (LDV) could measure the structural dynamic response of a wind turbine that was parked in the field. We performed a series of preliminary tests in the lab to determine the basic limitations of the LDV for this application. We then instrumented an installed parked horizontal axis wind turbine with accelerometers to determine the natural frequencies, damping, and mode shapes of the wind turbine and rotor as a baseline for the LDV and our other tests. We also wanted to determine if LDV modal information could be obtained from a naturally (wind) excited wind turbine. We compared concurrently obtained accelerometer and LDV data in an attempt to assess the quality of the LDV data. Our test results indicate the LDV can be successfully used in the field environment of an installed wind turbine, but with a few restrictions. We were successful in obtaining modal information from a naturally (wind) excited wind turbine in the field, but the data analysis requires a large number of averaged data sets to obtain reasonable results. An ultimate goal of this continuing project is to develop a technique that will monitor the health of a structure, detect damage, and hopefully predict an impending component failure.

  6. A magnetic field parameter study of turbulence-driven solar wind

    NASA Astrophysics Data System (ADS)

    Woolsey, L. N.; Cranmer, S. R.

    2012-12-01

    The solar wind has traditionally been described by two components that are separated by wind speed at 1 AU. Coronal holes, which are characterized by superradial expansion and low densities, are held as the source of fast solar wind (v > 600 km/s). Slow solar wind (v < 400 km/s) has often been attributed to sources in the streamer belt, but recent progress suggests that perhaps pseudostreamers or the edges of coronal holes may contribute significantly to this slower population. Further debate pertains to the mechanism that accelerates the solar wind, and a key question is whether the two populations arise due to A) two distinct acceleration processes or B) a single process occurring in regions of differing magnetic geometries. In this project, we investigate the latter possibility. We use the code ZEPHYR (Cranmer et al. 2007) to compute solar wind properties from an input of magnetic field strength as a function of height. This code produces self-consistent models of the solar wind. Turbulence caused by the reflection of Alfven waves cascades to the smallest scales and dissipates heat to the corona. The gas- and wave-pressure gradients accelerate the wind. We vary the magnetic field geometry input by specifying the strengths at four to five heights in the chromosphere and corona and using a spline interpolation to create a smooth radial dependence of the magnetic field in each flux tube. The range of field strengths is constrained by potential field source surface models using harmonic coefficients from the Wilcox Solar Observatory. We seek to better understand current correlations between solar wind properties while seeking new relationships. Currently, the anticorrelation between expansion factor and wind speed takes into account only the magnetic field strength at the photospheric base and at the source surface (Wang & Sheeley 1990). However, we look for relations that are based on different ratios of magnetic field strengths or other aspects of the magnetic

  7. Stakeholder Organizations: Hurricane Katrina and the New Orleans Public Schools

    ERIC Educational Resources Information Center

    Beabout, Brian

    2007-01-01

    In the aftermath of Hurricane Katrina, the district temporarily lost 100% of its students and did not reopen a single school for more than two months. As it became apparent that the district was not prepared to bring the schools back from such a devastating blow, educators began to see a silver lining in Katrina's dark clouds. State School Board…

  8. Breakup of New Orleans Households after Hurricane Katrina

    ERIC Educational Resources Information Center

    Rendall, Michael S.

    2011-01-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household breakup resulting from Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads…

  9. Toward Transformative Learning: An Inquiry into the Work and Subsequent Learning Experiences of Individuals Who Assisted Hurricane Katrina Evacuees

    ERIC Educational Resources Information Center

    Ficks, David B., II.

    2010-01-01

    The purpose of this multi-case study was to examine in depth the personal and learning experiences of helping professionals and volunteer helpers when challenged to assist adult Hurricane Katrina evacuees and victims in the aftermath of the disaster. The study contributes theoretically, practically and substantively to the adult education field.…

  10. Simulation-based study of wind loads on semi-submersed object in ocean wave field

    NASA Astrophysics Data System (ADS)

    Xie, Shengbai; Yang, Di; Liu, Yi; Shen, Lian

    2016-01-01

    Wind forcing makes a vital contribution to the hydrodynamic loads on structures at sea. The flow physics is complex, involving interactions among surface water waves, turbulent wind, and semi-submersed object. We perform a simulation-based study on a canonical problem of wind past a semi-submersed rectangular prism with the focus on the wave effect, which is an essential factor in wind loads at sea but has been elusive. To tackle this problem, we develop a hybrid simulation method consisting of two parts: a precursor simulation of coupled wind and wave motions in the far field upstream to provide physical inflow condition, and a near-field simulation of the air and water motions around the object. The simulation method is validated through numerical tests and comparisons with data from the literature for different aspects of the code. This hybrid simulation method is then applied to study the effect of surface wave motions on the wind load on the object. Various wave conditions are considered, including pure wind-sea satisfying the Joint North Sea Wave Project spectrum as well as wind-sea mixed with long-wavelength ocean swells. The simulation results exhibit significant oscillations in the wind load on the object. The oscillations are found to correlate well with the incident wave motions and are particularly strong in the presence of swells. The underlying mechanism is explained through analyses on variations of wind speed with different wave phases and wave-correlated flow patterns of the wind when it impinges on the object. Our simulations also indicate that waves have an appreciable effect on the wake behind the object.

  11. A solar wind-based model of geomagnetic field fluctuations at a mid-latitude station

    NASA Astrophysics Data System (ADS)

    Lotz, S. I.; Cilliers, P. J.

    2015-01-01

    Anomalous quasi-DC currents known as geomagnetically induced currents (GIC), produced in electric power network infrastructure during geomagnetic storms, pose a risk to reliable power transmission and network integrity. The prediction of a geomagnetic field-derived proxy to GIC provides an attractive mitigation technique that does not require changes to network hardware. In this paper we present the development of two artificial neural network based models tasked with predicting variations in the X (northward) and Y (eastward) components of the geomagnetic field at Hermanus, South Africa, with only solar wind plasma and interplanetary magnetic field (IMF) parameters as input. The models are developed by iteratively selecting the best set of solar wind parameters to predict the fluctuations in X and Y. To predict the variation in X, IMF magnitude, solar wind speed, fluctuation in solar wind proton density and a IMF-BZ derived parameter are selected. To predict the variation in Y, IMF-BZ , solar wind speed, and fluctuation in IMF magnitude are selected. The difference between the sets of selected input parameters are explained by the dependence of eastward perturbations in geomagnetic field at middle latitudes on field aligned currents. Model performance is evaluated during three storms in 2012. The onset and main phases of storms are fairly accurately predicted, but in cases where prolonged southward IMF coincides with solar wind parameters that are slowly varying the model fails to predict the observed fluctuations.

  12. The effects of vortex structure and vortex translation on the tropical cyclone boundary layer wind field

    NASA Astrophysics Data System (ADS)

    Williams, Gabriel J.

    2015-03-01

    The effects of vortex translation and radial vortex structure in the distribution of boundary layer winds in the inner core of mature tropical cyclones are examined using a high-resolution slab model and a multilevel model. It is shown that the structure and magnitude of the wind field (and the corresponding secondary circulation) depends sensitively on the radial gradient of the gradient wind field above the boundary layer. Furthermore, it is shown that vortex translation creates low wave number asymmetries in the wind field that rotate anticyclonically with height. A budget analysis of the steady state wind field for both models was also performed in this study. Although the agradient force drives the evolution of the boundary layer wind field for both models, it is shown that the manner in which the boundary layer flow responds to this force differs between the two model representations. In particular, the inner core boundary layer flow in the slab model is dominated by the effects of horizontal advection and horizontal diffusion, leading to the development of shock structures in the model. Conversely, the inner core boundary layer flow in the multilevel model is primarily influenced by the effects of vertical advection and vertical diffusion, which eliminates shock structures in this model. These results further indicate that special care is required to ensure that qualitative applications from slab models are not unduly affected by the neglect of vertical advection. This article was corrected on 31 MAR 2015. See the end of the full text for details.

  13. Interplanetary Magnetic Field Power Spectrum Variations in the Inner Heliosphere: A Wind and MESSENGER Study

    NASA Technical Reports Server (NTRS)

    Szabo, Adam; Koval, A.

    2011-01-01

    The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the similar observations made by the MESSENGER spacecraft in the inner heliosphere affords an opportunity to compare magnetic field power spectral density variations as a function of radial distance from the Sun under different solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the approx.2 Hz limit above which digitization noise becomes apparent. The powe'r spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions. Wind and MESSENGER magnetic fluctuations are compared for times when the two spacecraft are close to radial and Parker field alignment. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed.

  14. Effects of Hurricane Katrina on the forest structure of taxodium distichum swamps of the Gulf Coast, USA

    USGS Publications Warehouse

    Middleton, B.A.

    2009-01-01

    Hurricane Katrina pushed mixed Taxodium distichum forests toward a dominance of Taxodium distichum (baldcypress) and Nyssa aquatica (water tupelo) because these species had lower levels of susceptibility to wind damage than other woody species. This study documents the volume of dead versus live material of woody trees and shrubs of T. distichum swamps following Hurricane Katrina along the Gulf Coast of Mississippi and Louisiana. Pearl River Wildlife Management Area near Canton, Mississippi had the highest winds of the study areas, and these forests were located in the northeast quadrant of Hurricane Katrina (sustained wind 151 kph (94 mph)). Jean Lafitte National Historical Park and Preserve south of New Orleans had medium to high winds (sustained winds 111 kph (69 mph) at the New Orleans lakefront). Cat Island National Wildlife Refuge had a lower level of winds and was positioned on the western edge of the storm. The forests at Pearl River and to a lesser extent at Jean Lafitte had the highest amount of structural damage in the study. For Cat Island, Jean Lafitte, and Pearl River, the total volume of dead material (debris) was 50, 80, and 370 m3 ha-1, respectively. The ratio of dead to live volume was 0.010, 0.082, and 0.039, respectively. For both of the dominant species, T. distichum and N. aquatica, the percentage of dead to live volume was less than 1. Subdominant species including Acer rubrum, Liquidambar styraciflua, Quercus lyrata, and Quercus nigra were more damaged by the storm at both Pearl River and Jean Lafitte. Only branches were damaged by Hurricane Katrina at Cat Island. Shrubs such as Morella cerifera, Euonymous sp., and Vaccinium sp. were often killed by the storm, while other species such as Cephalanthus occidentalis, Forestiera acuminata, and Cornus florida were not killed. Despite the fact that Hurricane Katrina was a Category 3 storm and struck Pearl River and Jean Lafitte fairly directly, dominant species of the T. distichum swamps were

  15. Meteorological field measurements at potential and actual wind turbine sites

    SciTech Connect

    Renne, D.S.; Sandusky, W.F.; Hadley, D.L.

    1982-09-01

    An overview of experiences gained in a meteorological measurement program conducted at a number of locations around the United States for the purpose of site evaluation for wind energy utilization is provided. The evolution of the measurement program from its inception in 1976 to the present day is discussed. Some of the major accomplishments and areas for improvement are outlined. Some conclusions on research using data from this program are presented.

  16. The stellar wind velocity field of HD 77581

    NASA Astrophysics Data System (ADS)

    Manousakis, A.; Walter, R.

    2015-12-01

    Aims: The early acceleration of stellar winds in massive stars is poorly constrained. The scattering of hard X-ray photons emitted by the pulsar in the high-mass X-ray binary Vela X-1 can be used to probe the stellar wind velocity and density profile close to the surface of its supergiant companion HD 77581. Methods: We built a high signal-to-noise and high resolution hard X-ray lightcurve of Vela X-1 measured by Swift/BAT over 300 orbital periods of the system and compared it with the predictions of a grid of hydrodynamic simulations. Results: We obtain very good agreement between observations and simulations for a narrow set of parameters, implying that the wind velocity close to the stellar surface is twice higher than usually assumed with the standard beta law. Locally a velocity gradient of β ~ 0.5 is favoured. Even if still incomplete, hydrodynamic simulations successfully reproduce several observational properties of Vela X-1.

  17. Field Calibration of Wind Direction Sensor to the True North and Its Application to the Daegwanryung Wind Turbine Test Sites

    PubMed Central

    Lee, Jeong Wan

    2008-01-01

    This paper proposes a field calibration technique for aligning a wind direction sensor to the true north. The proposed technique uses the synchronized measurements of captured images by a camera, and the output voltage of a wind direction sensor. The true wind direction was evaluated through image processing techniques using the captured picture of the sensor with the least square sense. Then, the evaluated true value was compared with the measured output voltage of the sensor. This technique solves the discordance problem of the wind direction sensor in the process of installing meteorological mast. For this proposed technique, some uncertainty analyses are presented and the calibration accuracy is discussed. Finally, the proposed technique was applied to the real meteorological mast at the Daegwanryung test site, and the statistical analysis of the experimental testing estimated the values of stable misalignment and uncertainty level. In a strict sense, it is confirmed that the error range of the misalignment from the exact north could be expected to decrease within the credibility level.

  18. Magnetic field sector structure and origins of solar wind streams in 2012

    NASA Astrophysics Data System (ADS)

    Shugay, Yulia; Slemzin, Vladimir; Veselovsky, Igor

    2014-08-01

    The origins of the solar wind and the interplanetary magnetic field sector structure in the beginning of the magnetic polarity reversal of 24th solar cycle were investigated using the Wilcox Solar Observatory magnetic field measurements and their products as well as the solar wind data from ACE and the SDO/AIA EUV images. The dominance of the quadrupole harmonics in the solar magnetic field in this period resulted in a four-sector structure of the interplanetary magnetic field. The dominating source of recurrent high-speed solar wind stream was a large trans-equatorial coronal hole of negative polarity evolving in the course of the polarity reversal process. The contribution of ICMEs to the high-speed solar wind did not exceed 17% of the total flux. The solar wind density flux averaged over the year amounted to 1 × 108 cm-2 s-1 which is considerably lower than the typical long-term value (2-4 × 108 cm-2 s-1). The slow-speed component of solar wind density flux constituted in average more than 68% of the total flux, the high-speed component was about 10%, reaching the maximum of 32% in some Carrington rotations.

  19. Spatial interpolation of wind fields in a stably stratified atmospheric boundary layer using OpenFOAM

    NASA Astrophysics Data System (ADS)

    Sauter, Tobias; Obleitner, Friedrich

    2014-05-01

    The knowledge of the spatial distribution of meteorological fields in complex terrain is required for a large number of meteorological and glaciological applications. Unfortunately, in most cases the spatial distribution of observations is sparse, and consequently insufficient to reliably estimate the wind field by common interpolation schemes. The synergetic relationship between the complex terrain and local wind systems, can lead to intense gap flows, channeling effects, katabatic flows and even flow blocking events. In order to take these effects into account, the computation of the three-dimensional flow pattern is necessary. The purpose of the current study is to develop and evaluate the performance of a two-step wind interpolation scheme for stably stratified flows. In a first step, a initial wind field is estimated from in-situ observations and radio-sounding measurements. In the second step, a buoyancy-driven flow solver is used to account for the kinematic effects of the terrain, slope flows and blocking effects. The solver is then initialized by the prior estimated initial wind fields. The steady-state incompressible solver is developed using the open source computational fluid dynamic software OpenFOAM. The proposed approach was applied and evaluated at the Kongsvegen glacier in Svalbard for the summer period 2011. Dynamical and thermodynamical effects, such as katabatic winds, lee and gap flows were well represented. The results show promising potential for further scientific investigations.

  20. Field and wind tunnel modeling of an idealized street canyon flow

    NASA Astrophysics Data System (ADS)

    Blackman, K.; Perret, L.; Savory, E.; Piquet, T.

    2015-04-01

    The present work examines the flow field in a simple street canyon that has been modeled at full-scale and at 1:200 scale in a wind tunnel. It relies on the detailed analysis of statistics of both flows including two-point correlation coefficients, an approach not commonly done for canyon flows. Comparison between the field and wind tunnel study has demonstrated good agreement for the mean velocity and turbulence statistics, which are typically within 20%. However, significant differences in the along-canyon mean and turbulent components have been observed and are shown to be a result of the changing of the ambient wind direction and low frequency motion present in the field. As the wind direction changes over time the result is a channeling of flow along the canyon axis. This phenomenon cannot be accurately reproduced by the wind tunnel model, which produces nominally 2D flow. The turbulence dynamics were investigated through two-point spatial correlation of the streamwise, spanwise and vertical components, which show agreement to within 15-30% between the field and wind tunnel results. From estimation of boundary layer log-law parameters it has been shown that using a single point reference velocity measurement at 10 m height to estimate the boundary layer log-law parameters is unreliable in the present case.

  1. Aerodynamic roughness measured in the field and simulated in a wind tunnel

    NASA Technical Reports Server (NTRS)

    Sullivan, Robert; Greeley, Ronald

    1992-01-01

    This study evaluates how well values of aerodynamic surface roughness, z sub 0, measured over scale models in wind tunnels correlate with values of z sub 0 measured at full scale in the field. A field experiment was conducted in which values of z sub 0 and u* (wind friction speed) were measured over three arrays of non-erodible roughness elements on a dry lake bed. Wind profiles were measured by ten anemometers on a 15 m mast under thermally neutral atmospheric conditions. Values of z sub 0 increased from .00014 m (dry lake bed only) to .026 m with increasing roughness element density. The three roughness element arrays were simulated at 1/10 and 1/20 scale in an open-circuit atmospheric boundary-layer wind tunnel. Velocities were measured with a boundary-layer pitot-tube rake from the same relative position within the scale model arrays as the anemometers were relative to the field arrays. Each array at each scale was sampled three times at five freestream velocities. Average values of z sub 0 for each model array at each scale were compared with full-scale values of z sub 0 obtained in the field. The field vs. wind tunnel correspondence of z sub 0 is found to be z sub 0 field = 0.2661 x (z sub(0 model) x scale(exp -1))exp .8159.

  2. Distinct sensory representations of wind and near-field sound in the Drosophila brain

    PubMed Central

    Yorozu, Suzuko; Wong, Allan; Fischer, Brian J.; Dankert, Heiko; Kernan, Maurice J.; Kamikouchi, Azusa; Ito, Kei; Anderson, David J.

    2009-01-01

    Behavioral responses to wind are thought to play a critical role in controlling the dispersal and population genetics of wild Drosophila species1,2, as well as their navigation in flight3, but their underlying neurobiological basis is unknown. We show that Drosophila melanogaster, like wild-caught Drosophila strains4, exhibits robust wind-induced suppression of locomotion (WISL), in response to air currents delivered at speeds normally encountered in nature1,2. Here we identify wind-sensitive neurons in Johnston’s Organ (JO), an antennal mechanosensory structure previously implicated in near-field sound detection (reviewed in5,6). Using Gal4 lines targeted to different subsets of JO neurons7, and a genetically encoded calcium indicator8, we show that wind and near-field sound (courtship song) activate distinct populations of JO neurons, which project to different regions of the antennal and mechanosensory motor center (AMMC) in the central brain. Selective genetic ablation of wind-sensitive JO neurons in the antenna abolishes WISL behavior, without impairing hearing. Different neuronal subsets within the wind-sensitive population, moreover, respond to different directions of arista deflection caused by airflow and project to different regions of the AMMC, providing a rudimentary map of wind-direction in the brain. Importantly, sound- and wind-sensitive JO neurons exhibit different intrinsic response properties: the former are phasically activated by small, bi-directional, displacements of the aristae, while the latter are tonically activated by unidirectional, static deflections of larger magnitude. These different intrinsic properties are well suited to the detection of oscillatory pulses of near-field sound and laminar airflow, respectively. These data identify wind-sensitive neurons in JO, a structure that has been primarily associated with hearing, and reveal how the brain can distinguish different types of air particle movements, using a common sensory organ

  3. Effects of screens set characteristics on the flow field in a wind tunnel

    NASA Astrophysics Data System (ADS)

    Santos, A. M.; Souza, D. B.; Costa, F. O.; Farias, M. H.; Massari, P. de L.; Araújo, S.; Zanirath, Y. B.

    2016-07-01

    Wind tunnels have broad range of applications, and although there are common elements among the different types of tunnels, the layout and configuration of each facility will depend on its particular purpose. The flow conditioners section is a common component for all tunnels, and frequently contains flow straighteners and screens [1]. The role of screens is to minimize non uniformities or turbulence level on the flow field. In this work, the development and characteristics of the vertical velocity profile along an atmospheric wind tunnel length were evaluated. By using such data as initial reference, the effects, on the flow, when screens set is inserted on it were analyzed, in order to identify which changes could be done in the wind tunnel configuration to improve the characteristics of the flow field. Such atmospheric wind tunnel is a facility which belongs to the Brazilian National Metrology Institute INMETRO.

  4. Assimilating QuikSCAT Ocean Surface Winds with the Weather Research and Forecasting Model for Surface Wind-Field Simulation over the Chukchi/Beaufort Seas

    NASA Astrophysics Data System (ADS)

    Fan, Xingang; Krieger, Jeremy R.; Zhang, Jing; Zhang, Xiangdong

    2013-07-01

    To achieve a high-quality simulation of the surface wind field in the Chukchi/Beaufort Sea region, quick scatterometer (QuikSCAT) ocean surface winds were assimilated into the mesoscale Weather Research and Forecasting model by using its three-dimensional variational data assimilation system. The SeaWinds instrument on board the polar-orbiting QuikSCAT satellite is a specialized radar that measures ice-free ocean surface wind speed and direction at a horizontal resolution of 12.5 km. A total of eight assimilation case studies over two five-day periods, 1-5 October 2002 and 20-24 September 2004, were performed. The simulation results with and without the assimilation of QuikSCAT winds were then compared with QuikSCAT data available during the subsequent free-forecast period, coastal station observations, and North American Regional Reanalysis data. It was found that QuikSCAT winds are a potentially valuable resource for improving the simulation of ocean near-surface winds in the Chukchi/Beaufort Seas region. Specifically, the assimilation of QuikSCAT winds improved, (1) offshore surface winds as compared to unassimilated QuikSCAT winds, (2) sea-level pressure, planetary boundary-layer height, as well as surface heat fluxes, and (3) low-level wind fields and geopotential height. Verification against QuikSCAT data also demonstrated the temporal consistency and good quality of QuikSCAT observations.

  5. 8000 Ways to Model a Vortex: A Review of Hindcast Wind Field Methodologies

    NASA Astrophysics Data System (ADS)

    Sweeney, J.

    2014-12-01

    Hindcasts of cyclonic wind fields are crucial for extreme analysis in the oil and gas industry. Recent scientific developments have increased the number of parameterization options for tropical cyclone vortices, leading to well over 8000 permutations of model choices. Which is best? Also problematic is how best to blend modelled vortex winds into a global wind model (such as the Climate Forecast System Reanalysis (CFSR)) in order to resolve tropical cyclones to sufficient detail for wave modelling. Standard blending schemes can leave a 'moat' between the vortex and the CFSR circulation (see Figure 1 from TC Olivia 1996). Using a 35-year track database from the Australian Bureau of Meteorology, this study assesses model configurations and blending schemes against the most extensive measured meteorological dataset in the north-east Indian Ocean (largely commercial-in-confidence). The Holland profile models of 1980 and 2008 are two starting points, with other options examined for radius to maximum wind calculations, pressure-wind relationships, averaging periods, atmospheric profiles, gust factors, and asymmetry methods. Once a vortex is modelled, the winds are then fitted to the radius of gales and blended into the CFSR before further verification. Initial results support recent theoretical developments by Hu et al (2012), with additional results that call for a new asymmetry method and the separation of pressure and wind field modelling.

  6. Sensitivity of calculated odd nitrogen distributions to the diabatic wind fields

    NASA Technical Reports Server (NTRS)

    Boughner, R. E.; Callis, L. B., Jr.; Natarajan, M.

    1991-01-01

    This paper compares atmospheric total odd nitrogen and ozone computed with two different advective wind fields, one using climatological averages of ozone and temperature to obtain monthly averaged horizontal and vertical winds and the other using measurements from the LIMS instrument. Calculations using the former data show stronger poleward and downward motion in the winter season compared to those using the LIMS data. This leads to NO(y) mixing ratios in the lower stratosphere that are about 20 percent larger in the polar regions of both hemispheres and about 40 percent higher in the equatorial region for climatological transport fields compared to those derived from LIMS data. Consequently, the NO(y) distributions calculated with the LIMS advective field show worse agreement with the NO(y) values inferred from the LIMS measurements than similar results obtained with the climatological wind field.

  7. ENHANCED DISSIPATION RATE OF MAGNETIC FIELD IN STRIPED PULSAR WINDS BY THE EFFECT OF TURBULENCE

    SciTech Connect

    Takamoto, Makoto; Inoue, Tsuyoshi; Inutsuka, Shu-ichiro E-mail: inouety@phys.aoyama.ac.jp

    2012-08-10

    In this paper, we report on turbulent acceleration of the dissipation of the magnetic field in the post-shock region of a Poynting flux-dominated flow, such as the Crab pulsar wind nebula. We have performed two-dimensional resistive relativistic magnetohydrodynamics simulations of subsonic turbulence driven by the Richtmyer-Meshkov instability at the shock fronts of the Poynting flux-dominated flows in pulsar winds. We find that turbulence stretches current sheets which substantially enhances the dissipation of the magnetic field, and that most of the initial magnetic field energy is dissipated within a few eddy-turnover times. We also develop a simple analytical model for turbulent dissipation of the magnetic field that agrees well with our simulations. The analytical model indicates that the dissipation rate does not depend on resistivity even in the small resistivity limit. Our findings can possibly alleviate the {sigma}-problem in the Crab pulsar wind nebulae.

  8. Interplanetary and Interstellar Dust Observed by the Wind/WAVES Electric Field Instrument

    NASA Technical Reports Server (NTRS)

    Malaspina, David; Horanyi, M.; Zaslavsky, A.; Goetz, K.; Wilson, L. B., III; Kersten, K.

    2014-01-01

    Observations of hypervelocity dust particles impacting the Wind spacecraft are reported here for the first time using data from the WindWAVES electric field instrument. A unique combination of rotating spacecraft, amplitude-triggered high-cadence waveform collection, and electric field antenna configuration allow the first direct determination of dust impact direction by any spacecraft using electric field data. Dust flux and impact direction data indicate that the observed dust is approximately micron-sized with both interplanetary and interstellar populations. Nanometer radius dust is not detected by Wind during times when nanometer dust is observed on the STEREO spacecraft and both spacecraft are in close proximity. Determined impact directions suggest that interplanetary dust detected by electric field instruments at 1 AU is dominated by particles on bound trajectories crossing Earths orbit, rather than dust with hyperbolic orbits.

  9. Ion exchange with the solar wind for planets with negligible intrinsic magnetic fields

    NASA Technical Reports Server (NTRS)

    Nisbet, J. S.

    1979-01-01

    The exchange of ions between the ionosphere of a planet with negligible intrinsic magnetic field, and the solar wind is examined. It is suggested that a balance exists between the outflow of ionospheric ions at the plasmapause and ions from the solar wind in a restricted region close to the subsolar point. This results in a current system towards the subsolar point on the surface of the ionopause and a toroidal magnetic field. Simple calculations are made of the current and field configuration that might result from the system for conditions similar to those encountered on the Viking 1 and 2 transits of the Mars ionosphere.

  10. On the alignment of plasma anisotropies and the magnetic field direction in the solar wind

    NASA Technical Reports Server (NTRS)

    Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Gosling, J. T.; Ness, N. F.

    1977-01-01

    One year's Imp 6 solar wind plasma and magnetic field data are examined to determine whether anisotropies in particle velocity distributions are aligned with the measured interplanetary magnetic field vector. Alignment of components in the analysis plane was generally found to be excellent whenever plasma parameter magnitudes were larger than determination uncertainties, although some spread exists (typical rms approximately equal to 10 deg). By assuming cylindrical symmetry about the simultaneously measured magnetic field vector during the 1-year interval under study, three-dimensional values of selected solar wind plasma thermal parameters were constructed from the two-dimensional plasma measurements, and the statistical properties of their distributions have been tabulated.

  11. The population of the magnetosphere by solar winds ions when the interplanetary magnetic field is northward

    NASA Technical Reports Server (NTRS)

    Richard, Robert L.; Walker, Raymond J.; Ashour-Abdalla, Maha

    1994-01-01

    We have examined some possible entry mechanisms of solar wind ions into the magnetosphere by calculating the trajectories of thousands of non-interacting ions in the magnetic and electric fields from a three dimensional global magnetohydrodynamic (MHD) simulation of the magnetosphere and the magnetosheath, under northward interplanetary magnetic field (IMF) conditions. Particles, launched in the solar wind, entered the magnetosphere and formed the low latitude boundary layer (LLBL), plasma sheet and a region of trapped particles near the Earth. The densities and temperatures we obtained in these regions were realistic, with the exception of trapped particle densities. The dominant entry mechanism was convection into the magnetosphere on reconnecting field lines.

  12. What determines the direction of minimum variance of the magnetic field fluctuations in the solar wind?

    NASA Technical Reports Server (NTRS)

    Grappin, R.; Velli, M.

    1995-01-01

    The solar wind is not an isotropic medium; two symmetry axis are provided, first the radial direction (because the mean wind is radial) and second the spiral direction of the mean magnetic field, which depends on heliocentric distance. Observations show very different anisotropy directions, depending on the frequency waveband; while the large-scale velocity fluctuations are essentially radial, the smaller scale magnetic field fluctuations are mostly perpendicular to the mean field direction, which is not the expected linear (WkB) result. We attempt to explain how these properties are related, with the help of numerical simulations.

  13. Global disturbance of the transient magnetic field associated with thermospheric storm winds on March 23, 1979

    SciTech Connect

    Fambitakoye, O. ); Menvielle, M. ); Mazaudier, C. Centre de Recherche sur la Physique de l'Environnement, Saint Maur des Fosses )

    1990-09-01

    During large magnetic storms, wind disturbances produces by auroral phenomena can affect the whole thermospheric circulation and associated ionospheric dynamo currents for many hours after the end of the storm. This paper presents a morphological analysis of the ground magnetic field disturbance related to the storm winds observed on March 23, 1979, the day after the Coordinated Data Analysis Workshop (CDAW) 6 events. The disturbance in the magnetic field variations is observed on a planetary scale, and its pattern does not correspond to that of the regular field variations related to the undisturbed atmospheric dynamo.

  14. Earth Observations to Assess Impact of Hurricane Katrina on John C. Stennis Space Center

    NASA Technical Reports Server (NTRS)

    Graham, William D.; Ross, Kenton W.

    2007-01-01

    The peril from hurricanes to Space Operations Centers is real and is forecast to continue; Katrina, Rita, and Wilma of 2005 and Charley, Frances, Ivan, and Jeanne of 2004 are sufficient motivation for NASA to develop a multi-Center plan for preparedness and response. As was demonstrated at SSC (Stennis Space Center) in response to Hurricane Katrina, NASA Centers are efficiently activated as local command centers, playing host to Federal and State agencies and first responders to coordinate and provide evacuation, relocation, response, and recovery activities. Remote sensing decision support provides critical insight for managing NASA infrastructure and for assisting Center decision makers. Managers require geospatial information to manage the federal city. Immediately following Katrina, SSC s power and network connections were disabled, hardware was inoperative, technical staff was displaced and/or out of contact, and graphical decision support tools were non-existent or less than fully effective. Despite this circumstance, SSC EOC (Emergency Operations Center) implemented response operations to assess damage and to activate recovery plans. To assist Center Managers, the NASA ASP (Applied Sciences Program) made its archive of high-resolution data over the site available. In the weeks and months after the immediate crisis, NASA supplemented this data with high-resolution, post-Katrina imagery over SSC and much of the affected coastal areas. Much of the high-resolution imagery was made available through the Department of Defense Clear View contract and was distributed through U.S. Geological Survey Center for Earth Resources Observation and Science "Hurricane Katrina Disaster Response" Web site. By integrating multiple image data types with other information sources, ASP applied an all-source solutions approach to develop decision support tools that enabled managers to respond to critical issues, such as expedient access to infrastructure and deployment of resources

  15. Galactic cosmic ray currents and magnetic field irregularity degree in high-speed solar wind streams

    NASA Technical Reports Server (NTRS)

    Kuzmin, A. I.; Samsonov, I. S.; Samsonova, Z. N.

    1985-01-01

    Currents of galactic cosmic rays (GCR) obtained by global survey method are analyzed. The cases of almost total disappearance of GCR currents are compared with the results of direct measurements of the solar wind parameters. The conclusion is made on a restricted application of the convective-diffusive mechanism of the GCR modulation by the solar wind during the occurrence of stationary and regular magnetic fields in the interplanetary medium.

  16. Probabilistic Path Planning of Montgolfier Balloons in Strong, Uncertain Wind Fields

    NASA Technical Reports Server (NTRS)

    Wolf, Michael; Blackmore, James C.; Kuwata, Yoshiaki

    2011-01-01

    Lighter-than-air vehicles such as hot-air balloons have been proposed for exploring Saturn s moon Titan, as well as other bodies with significant atmospheres. For these vehicles to navigate effectively, it is critical to incorporate the effects of surrounding wind fields, especially as these winds will likely be strong relative to the control authority of the vehicle. Predictive models of these wind fields are available, and previous research has considered problems of planning paths subject to these predicted forces. However, such previous work has considered the wind fields as known a priori, whereas in practical applications, the actual wind vector field is not known exactly and may deviate significantly from the wind velocities estimated by the model. A probabilistic 3D path-planning algorithm was developed for balloons to use uncertain wind models to generate time-efficient paths. The nominal goal of the algorithm is to determine what altitude and what horizontal actuation, if any is available on the vehicle, to use to reach a particular goal location in the least expected time, utilizing advantageous winds. The solution also enables one to quickly evaluate the expected time-to-goal from any other location and to avoid regions of large uncertainty. This method is designed for balloons in wind fields but may be generalized for any buoyant vehicle operating in a vector field. To prepare the planning problem, the uncertainty in the wind field is modeled. Then, the problem of reaching a particular goal location is formulated as a Markov decision process (MDP) using a discretized space approach. Solving the MDP provides a policy of what actuation option (how much buoyancy change and, if applicable, horizontal actuation) should be selected at any given location to minimize the expected time-to-goal. The results provide expected time-to-goal values from any given location on the globe in addition to the action policy. This stochastic approach can also provide

  17. Field Testing: Independent, Accredited Testing and Validation for the Wind Industry (Fact Sheet)

    SciTech Connect

    Not Available

    2011-11-01

    This fact sheet describes the field testing capabilities at the National Wind Technology Center (NWTC). NREL's specialized facilities and personnel at the NWTC provide the U.S. wind industry with scientific and engineering support that has proven critical to the development of wind energy for U.S. energy needs. The NWTC's specialized field-testing capabilities have evolved over 30 years of continuous support by the U.S. Department of Energy Wind and Hydropower Technologies Program and long standing industry partnerships. The NWTC provides wind industry manufacturers, developers, and operators with turbine and component testing all in one convenient location. Although industry utilizes sophisticated modeling tools to design and optimize turbine configurations, there are always limitations in modeling capabilities, and testing is a necessity to ensure performance and reliability. Designs require validation and testing is the only way to determine if there are flaws. Prototype testing is especially important in capturing manufacturing flaws that might require fleet-wide retrofits. The NWTC works with its industry partners to verify the performance and reliability of wind turbines that range in size from 400 Watts to 3 megawatts. Engineers conduct tests on components and full-scale turbines in laboratory environments and in the field. Test data produced from these tests can be used to validate turbine design codes and simulations that further advance turbine designs.

  18. Solar wind interaction effects on the magnetic fields around Mars: Consequences for interplanetary and crustal field measurements

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Ma, Y.-J.; Brain, D. A.; Ulusen, D.; Lillis, R. J.; Halekas, J. S.; Espley, J. R.

    2015-11-01

    The first unambiguous detections of the crustal remanent magnetic fields of Mars were obtained by Mars Global Surveyor (MGS) during its initial orbits around Mars, which probed altitudes to within ∼110 km of the surface. However, the majority of its measurements were carried out around 400 km altitude, fixed 2 a.m. to 2 p.m. local time, mapping orbit. While the general character and planetary origins of the localized crustal fields were clearly revealed by the mapping survey data, their effects on the solar wind interaction could not be investigated in much detail because of the limited mapping orbit sampling. Previous analyses (Brain et al., 2006) of the field measurements on the dayside nevertheless provided an idea of the extent to which the interaction of the solar wind and planetary fields leads to non-ideal field draping at the mapping altitude. In this study we use numerical simulations of the global solar wind interaction with Mars as an aid to interpreting that observed non-ideal behavior. In addition, motivated by models for different interplanetary field orientations, we investigate the effects of induced and reconnected (planetary and external) fields on the Martian field's properties derived at the MGS mapping orbit altitude. The results suggest that inference of the planetary low order moments is compromised by their influence. In particular, the intrinsic dipole contribution may differ from that in the current models because the induced component is so dominant.

  19. Energy-modeled flight in a wind field

    SciTech Connect

    Feldman, M.A.; Cliff, E.M.

    1994-12-31

    Optimal shaping of aerospace trajectories has provided the motivation for much modern study of optimization theory and algorithms. Current industrial practice favors approaches where the continuous-time optimal control problem is transcribed to a finite-dimensional nonlinear programming problem (NLP) by a discretization process. Two such formulations are implemented in the POST and the OTIS codes. In the present paper we use a discretization that is specially adapted to the flight problem of interest. Among the unique aspects of the present discretization are: a least-squares formulation for certain kinematic constraints; the use of an energy ideas to enforce Newton`s Laws; and, the inclusion of large magnitude horizontal winds. In the next section we shall provide a description of the flight problem and its NLP representation. Following this we provide some details of the constraint formulation. Finally, we present an overview of the NLP problem.

  20. Magnetic Cloud Field Intensities and Solar Wind Velocities

    NASA Technical Reports Server (NTRS)

    Gonzalez, Walter D.; Clau de Gonzalez, Alicia D.; Tsurutani, Bruce T.; Arballo, John K.

    1997-01-01

    For the sets of magnetic clouds studied in this work we have shown that there is a general relationship between their magnetic fields strength and velocities. With a clear tendency that the faster the speed of the cloud the higher the magnetic field.

  1. Hurricane Wind Field Measurements with Scanning Airborne Doppler Lidar During CAMEX-3

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Cutten, D. R.; Howell, J. N.; Darby, L. S.; Hardesty, R. M.; Traff, D. M.; Menzies, R. T.

    2000-01-01

    During the 1998 Convection and Moisture Experiment (CAMEX-3), the first hurricane wind field measurements with Doppler lidar were achieved. Wind fields were mapped within the eye, along the eyewall, in the central dense overcast, and in the marine boundary layer encompassing the inflow region. Spatial coverage was determined primarily by cloud distribution and opacity. Within optically-thin cirrus slant range of 20- 25 km was achieved, whereas no propagation was obtained during penetration of dense cloud. Measurements were obtained with the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) on the NASA DC-8 research aircraft. MACAWS was developed and operated cooperatively by the atmospheric lidar remote sensing groups of NOAA Environmental Technology Laboratory, NASA Marshall Space Flight Center, and Jet Propulsion Laboratory. A pseudo-dual Doppler technique ("co-planar scanning") is used to map the horizontal component of the wind at several vertical levels. Pulses from the laser are directed out the left side of the aircraft in the desired directions using computer-controlled rotating prisms. Upon exiting the aircraft, the beam is completely eyesafe. Aircraft attitude and speed are taken into account during real-time signal processing, resulting in determination of the ground-relative wind to an accuracy of about 1 m/s magnitude and about 10 deg direction. Beam pointing angle errors are about 0.1 deg, equivalent to about 17 m at 10 km. Horizontal resolution is about 1 km (along-track) for typical signal processor and scanner settings; vertical resolution varies with range. Results from CAMEX-3 suggest that scanning Doppler wind lidar can complement airborne Doppler radar by providing wind field measurements in regions that are devoid of hydrometeors. At present MACAWS observations are being assimilated into experimental forecast models and satellite Doppler wind lidar simulations to evaluate the relative impact.

  2. Interaction of solar wind with Mercury and its magnetic field. [as observed by Mariner 10 space probe

    NASA Technical Reports Server (NTRS)

    Ness, N. F.; Behannon, K. W.; Lepping, R. P.; Whang, Y. C.

    1976-01-01

    A brief review is presented of magnetic field and solar wind electron observations by Mariner 10 spacecraft. The intrinsic magnetic field of the planet Mercury and the implications of such a field for the planetary interior are also discussed.

  3. Mechanisms for Secondary Eyewall Formation in Tropical Cyclones: A Case Study of Hurricane Katrina (2005)

    NASA Astrophysics Data System (ADS)

    Garcia-Rivera, J. M.; Lin, Y.

    2013-05-01

    The Weather Research and Forecast (WRF) model is used to simulate the last eyewall replacement cycle (ERC) of Hurricane Katrina (2005) just before it's landfall in the Louisiana coastline. In this study, we pursue a complete understanding of the physics behind the secondary eyewall formation (SEF) in tropical cyclones. The simulation results show the occurrence of the early stages of an ERC in the simulated storm just before landfall. This confirms that with the appropriate set of physics parameterization schemes, grid spacing and initial conditions, the numerical model is able to reproduce ERCs on certain tropical cyclones with no data assimilation or extra data inputs. Strong updrafts are observed to converge in a ring outside the primary eyewall of Hurricane Katrina (2005) suggesting SEF during that period. The increase of divergence outside the primary eyewall with an outer-ring of convergence forming above the boundary layer can be part of the mechanisms that lead to SEF. Also, potential vorticity (PV) field is analyzed for its possible relationship with the development of the secondary eyewall. This detailed study of the pre-ERC events in the inner-core of Hurricane Katrina can build the foundations for testing some of the existing hypotheses for the development of secondary eyewalls leading to new ideas behind their formation.

  4. In situ magnetic field measurements during AMPTE solar wind Li(+) releases. [Active Magnetospheric Particle Tracer Explorers

    NASA Technical Reports Server (NTRS)

    Luehr, H.; Kloecker, N.; Southwood, D. J.; Acuna, M.; Haeusler, B.

    1986-01-01

    The effects of lithium ion releases on solar wind flow are investigated. The background field conditions during the releases on September 11 and 20, 1984 are discussed. The magnetic field data recorded by the Ion Release Module and United Kingdom Satellite are described. It is observed that the first release occurred on the field lines connecting to the earth's bow shock causing difficulty in separating the effects of natural large scale perturbations from the ion effects. In the second release, which occurred in a stable, ambient environment, the characteristics of a Venus-like perturbation of the magnetic field are detected. It is concluded that in both releases a field cavity is formed, the field transverse to the solar wind flow is amplified, and the transverse component is compressed.

  5. Interaction of Hurricane Katrina with Optically Complex Water in the Gulf of Mexico: Interpretation Using Satellite-Derived Inherent Optical Properties and Chlorophyll Concentration

    NASA Astrophysics Data System (ADS)

    Lyon, P. E.; Acker, J.; Hoge, F. E.; Shen, S.; Roffer, M.; Gawlikowski, G.

    2008-12-01

    When Hurricane Katrina passed over southern Florida, Florida Bay and the West Florida Shelf, and into the Gulf of Mexico, empirically derived chl a increases were observed in the Tortugas Gyre circulation feature, and in adjacent waters. Analysis of the empirically derived chl a increase within the gyre has been primarily attributed to initiation of a phytoplankton bloom promoted by nutrients upwelled by Katrina's winds. Detailed analysis of inherent optical properties (IOPs) derived from remotely-sensed radiances, however, indicated the interaction of Katrina with shallow coastal and shelf waters likely entrained waters with higher concentrations of chromophoric dissolved organic matter (CDOM) into the gyre circulation, augmenting the chl a signal. Storm-induced upwelling would also transport optically active CDOM to the surface. Increases in empirically derived chl a in the Florida coastal waters influenced by Katrina's winds were therefore partly due to increased absorption by CDOM. This analysis indicates that elevated empirically derived chl a in hurricane-influenced waters should not be unambiguously attributed to increased phytoplankton productivity, particularly in an optically complex coastal environment.

  6. The influence of the tropics on the prediction of ultralong waves. I - Tropical wind field

    NASA Technical Reports Server (NTRS)

    Baker, W. E.; Paegle, J.

    1983-01-01

    The effects of tropical wind data from the FGGE and tropical latent heating on numerical modeling of ultralong waves are considered in a two-part study. The model studied is the global fourth-order GLAS general circulation model, an energy-conserving format with horizontal differences calculated with fourth-order accuracy. Data assimilation experiments were performed with and without the wind data, with account taken of eastward and northward wind components, the geopotential height, and the relative humidity, all over pressure surfaces. The initial conditions were used to generate six pairs of forecasts, and the tropical wind error decreased after two days of prediction when the initial conditions contained the wind data. The deviations from the measured planetary wave data were attributed to differences in the initial rotational wind field, which varied on a three-day basis. The latent heat initial data had a five-day period and extended its influence beyond the tropical zone. The tropical heat sources sustained the tropical westerlies in the GLAS model, and removal of the tropical heat sources reversed the wind to easterlies.

  7. Turbine-scale wind field measurements using dual-Doppler lidar

    SciTech Connect

    Newsom, Rob K.; Berg, Larry K.; Shaw, William J.; Fischer, Marc

    2015-02-01

    Spatially resolved measurements of micro-scale winds are retrieved using scanning dual-Doppler lidar, and validated against independent in situ wind measurements. Data for this study were obtained during a month-long field campaign conducted at a site in north-central Oklahoma in November of 2010. Observational platforms include one heavily instrumented 60-m meteorological tower and two scanning coherent Doppler lidars. The lidars were configured to perform coordinated dual-Doppler scans surrounding the 60-m tower, and the resulting radial velocity observations were processed to retrieve the 3-component velocity vector field on surfaces defined by the intersecting scan planes. Raw radial velocity measurements from the lidars were calibrated by direct comparison to a sonic anemometer located at the 60 m level on the tower. Wind retrievals were performed using both calibrated and uncalibrated measurements, and validated against the 60-m sonic anemometer observations. Retrievals using uncalibrated radial velocity data show a significant slow bias in the wind speed of about 14%; whereas the retrievals using the calibrated data show a much smaller slow bias of 1.2%. Retrievals using either the calibrated or uncalibrated data exhibit negligible bias in the wind direction (<0.2o), and excellent correlation in the wind speeds (>0.96).

  8. Field-Aligned Current Sheet Motion and Its Correlation with Solar Wind Conditions and Geomagnetic Activities

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Le, G.; Boardsen, S. A.; Slavin, J. A.; Strangeway, R. J.

    2008-05-01

    Field-aligned currents (FACs) are the currents flowing into and out of the ionosphere which connect to the magnetosphere. They provide an essential linkage between the solar wind - magnetosphere system and the ionosphere, and the understanding of these currents is important for global magnetosphere dynamics and space weather prediction. The three spacecraft ST-5 constellation provides an unprecedented opportunity to study in situ FAC dynamics in time scales (10 sec to 10 min) that can not be achieved previously with single spacecraft studies or large-spaced conjugate spacecraft studies. In this study, we use the magnetic field observations during the whole ST-5 mission and their corresponding solar wind conditions to study the dependence of FAC current sheet motion and intensity on solar wind conditions. FAC peak current densities show very good correlations with some solar wind parameters, including IMF Bz, dynamic pressure, Ey, and some IMF angles, but not with other parameters. Instant FAC speeds show generally much weaker dependence on solar wind conditions comparing to FAC peak current densities. This obvious uncorrelation between FAC peak current densities and speeds implies that FAC peak current densities are more consistently controlled by solar wind conditions and geomagnetic activities, while FAC speeds are more oscillatory, sometimes with higher speeds during quieter times and lower speeds during more turbulent times.

  9. Wind field near complex terrain using numerical weather prediction model

    NASA Astrophysics Data System (ADS)

    Chim, Kin-Sang

    The PennState/NCAR MM5 model was modified to simulate an idealized flow pass through a 3D obstacle in the Micro- Alpha Scale domain. The obstacle used were the idealized Gaussian obstacle and the real topography of Lantau Island of Hong Kong. The Froude number under study is ranged from 0.22 to 1.5. Regime diagrams for both the idealized Gaussian obstacle and Lantau island were constructed. This work is divided into five parts. The first part is the problem definition and the literature review of the related publications. The second part briefly discuss as the PennState/NCAR MM5 model and a case study of long- range transport is included. The third part is devoted to the modification and the verification of the PennState/NCAR MM5 model on the Micro-Alpha Scale domain. The implementation of the Orlanski (1976) open boundary condition is included with the method of single sounding initialization of the model. Moreover, an upper dissipative layer, Klemp and Lilly (1978), is implemented on the model. The simulated result is verified by the Automatic Weather Station (AWS) data and the Wind Profiler data. Four different types of Planetary Boundary Layer (PBL) parameterization schemes have been investigated in order to find out the most suitable one for Micro-Alpha Scale domain in terms of both accuracy and efficiency. Bulk Aerodynamic type of PBL parameterization scheme is found to be the most suitable PBL parameterization scheme. Investigation of the free- slip lower boundary condition is performed and the simulated result is compared with that with friction. The fourth part is the use of the modified PennState/NCAR MM5 model for an idealized flow simulation. The idealized uniform flow used is nonhydrostatic and has constant Froude number. Sensitivity test is performed by varying the Froude number and the regime diagram is constructed. Moreover, nondimensional drag is found to be useful for regime identification. The model result is also compared with the analytic

  10. Sensitivity of an oceanic general circulation model forced by satellite wind stress fields

    NASA Astrophysics Data System (ADS)

    Grima, Nicolas; Bentamy, Abderrahim; Katsaros, Kristina; Quilfen, Yves; Delecluse, Pascale; Levy, Claire

    1999-04-01

    Satellite wind and wind stress fields at the sea surface, derived from the scatterometers on European Remote Sensing satellites 1 and 2 (ERS-1 and ERS-2) are used to drive the ocean general circulation model (OGCM) "OPA" in the tropical oceans. The results of the impact of ERS winds are discussed in terms of the resulting thermocline, current structures, and sea level anomalies. Their adequacy is evaluated on the one hand by comparison with simulations forced by the Arpege-Climat model and on the other hand by comparison with measurements of the Tropical Atmosphere-Ocean (TAO) buoy network and of the TOPEX/Poseidon altimeter. Regarding annual mean values, the thermal and current responses of the OGCM forced by ERS winds are in good agreement with the TAO buoy observations, especially in the central and eastern Pacific Ocean. In these regions the South Equatorial Current, the Equatorial Undercurrent, and the thermocline features simulated by the OGCM forced by scatterometer wind fields are described. The impact of the ERS-1 winds is particularly significant to the description of the main oceanic variability. Compared to the TAO buoy observations, the high-frequency (a few weeks) and the low-frequency of the thermocline and zonal current variations are described. The correlation coefficients between the time series of the thermocline simulated by ERS winds and that observed by the TAO buoy network are highly significant; their mean value is 0.73, over the whole basin width, while it is 0.58 between Arpege model simulation and buoy observations. At the equator the time series of the zonal current simulated by the ERS winds, at three locations (110°W, 140°W, and 165°E) and at two depths, are compared to the TAO current meter and acoustic Doppler current profiler (ADCP) measurements. The mean value of the significant correlation coefficients computed with the in situ measurements is 0.72 for ERS, while it is 0.51 for the Arpege-Climat model. Thus ERS wind fields

  11. Damage to offshore infrastructure in the Gulf of Mexico by hurricanes Katrina and Rita

    NASA Astrophysics Data System (ADS)

    Cruz, A. M.; Krausmann, E.

    2009-04-01

    and occurred on both fixed and floating platforms. The total number of pipelines damaged by Hurricanes Katrina and Rita as of May 1, 2006, was 457. Pipeline damage was mostly caused by damage or failure of the host platform or its development and production piping, the impact of dragging and displaced objects, and pipeline interaction at a crossing. Damage to pipelines was a major contributing factor in delaying start up of offshore oil and gas production. During our analysis of the NRC database we identified 611 reported hazardous-materials releases directly attributed to offshore platforms and pipelines affected by the two hurricanes. There were twice as many releases during Hurricane Katrina than during Rita; 80% or more of the releases reported in the NRC database occurred from platforms. Our analysis suggests that the majority of releases were petroleum products, such as crude oil and condensate, followed by natural gas. In both Katrina and Rita, releases were more likely in the front, right quadrant of the storm. Storm-surge values were highest closer to the coastline. This may help explain the higher number of releases in shallow waters. The higher number of hazardous-materials releases from platforms during Katrina may partly be attributed to the higher wind speeds for this storm as it approached land.

  12. Predicting wind field in the Bay of Bengal from scatterometer observations using genetic algorithm

    NASA Astrophysics Data System (ADS)

    Sharma, Rashmi; Sarkar, Abhijit; Agarwal, Neeraj; Kumar, Raj; Basu, Sujit

    2007-02-01

    A technique based on genetic algorithm (GA) is applied for predicting wind field in the Bay of Bengal (BOB) using satellite scatterometer observations. Empirical orthogonal function (EOF) analysis is used for compressing the spatial variability into a set of eigenmodes. The time series of each principal component (PC) is subjected to singular spectrum analysis (SSA) and GA is applied to the resulting filtered time series. The forecast PCs are weighted by the spatial eigenmodes for computing forecast wind fields. Predictions made up to 5 days in advance are found to be superior to forecast by persistence method.

  13. Signature of open magnetic field lines in the extended solar corona and of solar wind acceleration

    NASA Technical Reports Server (NTRS)

    Antonucci, E.; Giordano, S.; Benna, C.; Kohl, J. L.; Noci, G.; Michels, J.; Fineschi, S.

    1997-01-01

    The observations carried out with the ultraviolet coronagraph spectrometer onboard the Solar and Heliospheric Observatory (SOHO) are discussed. The purpose of the observations was to determine the line of sight and radial velocity fields in coronal regions with different magnetic topology. The results showed that the regions where the high speed solar wind flows along open field lines are characterized by O VI 1032 and HI Lyman alpha 1216 lines. The global coronal maps of the line of sight velocity were reconstructed. The corona height, where the solar wind reaches 100 km/s, was determined.

  14. An integrated approach for wind fields assessment in coastal areas, based on bioindicators, CFD modeling, and observations

    NASA Astrophysics Data System (ADS)

    Meneses, Bruno M.; Lopes, António

    2015-12-01

    Wind-deformed trees can be good bioindicators of the mean wind speed and prevailing wind directions. The current research used bioindicators, computational fluid dynamics (CFD), and linear models to assess the wind fields in the windy coastal area of Cascais/Portugal. The main objectives of this research are to assess mean speed and directions of winds by using bioindicators and modeling techniques and to correlate both results in order to assess the best methods. The results obtained with the bioindicators showed that carpeting, the most severe deformation, was observed near the shoreline showing that the highest wind speeds are felt in this sector. Inland, where the winds have lower mean speeds, flagging forms are more frequent. When correlated with the bioindicators, the linear model gave better results than CFD models. We can conclude that in areas with good wind potential, the use of bioindicators can be a good alternative in the absence of wind data.

  15. Disaster Doctor From 9/11 to Katrina

    MedlinePlus

    ... from a hair brush." Ancient Egypt and Modern Analysis So he and his team developed OSIRIS, for ... research, as well as other forensic uses." Katrina Analysis Difficult, Poignant… Sherry found identifying the dead from ...

  16. Children and Trauma: A Post-Katrina and Rita Response

    ERIC Educational Resources Information Center

    Hebert, Barbara B.; Ballard, Mary B.

    2007-01-01

    Many children have struggled to cope with the traumatic experiences brought about by hurricanes Katrina and Rita. This article recounts how the authors intervened in the lives of children and families after the storms. (Contains 3 figures.)

  17. Genetics Experts Unite to I.D. Unknown Katrina Victims

    MedlinePlus

    ... Current Issue Past Issues Research News From NIH Genetics Experts Unite to I.D. Unknown Katrina Victims ... in the recent Advances in molecular biology and genetics," says team member Stephen Sherry, Ph.D., of ...

  18. EMERGENCY RESPONSE FOR PUBLIC WATER SUPPLIES AFTER HURRICANE KATRINA

    EPA Science Inventory

    Hurricane Katrina resulted in damage and destruction to local water supplies in Mississippi and Louisiana affecting millions of people. Immediately following the devastation, a multidisciplinary team of 30 EPA emergency response, research, and water program personnel joined force...

  19. ENVIRONMENTAL SAMPLING AND ANALYSIS IN THE AFTERMATH OF HURRICANE KATRINA

    EPA Science Inventory

    This presentation describes the environmental sampling completed by EPA in southeastern Louisiana after Hurricane Katrina caused major catastrophic damage. Presentation also describes EPA's Environmental Unit activities in Baton Rouge and New Orleans, LA, and Dallas, TX.

  20. The Magnetic Field of Mars and its Interaction with the Solar Wind

    NASA Technical Reports Server (NTRS)

    Le, Guan; Slavin, James A.

    2009-01-01

    The outermost layers of the Martian atmosphere are thought to be scientifically unique due to the large influences exerted by the highly dynamic lower atmosphere and the direct input of the solar wind from above. The nature of the solar wind interaction with the upper atmosphere is of particular interest because Mars lacks a global magnetic field, but is well shielded over some regions by strong crustal magnetic fields. Under such circumstances, the direct impact of solar wind plasma may have resulted in enhanced loss of volatiles over the ages including the components of water. The history of upper atmosphere and solar wind interaction measurements at Mars will be reviewed, recent results from the Mars Global Surveyor and Mars Express summarized, and prospects for new scientific advances enabled by the measurements that will be made by planned orbiter and penetrator missions. Special attention will be given to planetary magnetic field measurements, the measurement of ionospheric currents driven by the solar wind, and the role of space weather modeling and forecasting in the future of Mars exploration.

  1. Radial Dependence of Intermittency in the Fast Polar Solar Wind Magnetic Field Using PDFs

    NASA Astrophysics Data System (ADS)

    Pagel, C.; Balogh, A.

    2002-12-01

    The Ulysses spacecraft, in a polar orbit of the Sun, spent almost three years sampling the pure polar coronal fast wind at solar minimum between 1994 and 1996. Turbulence in coronal fast wind, unaffected by stream shears with slow solar wind, evolves more slowly than fast wind turbulence in the ecliptic and is a more homogenous system. However, it is still a highly intermittent and turbulent medium. We use the Castaing probability distribution to study the intermittent properties of the fast wind magnetic field components at different time lags within the inertial range, and present results on how intermittency in the magnetic field components depends on radial distance from the Sun. We find that for all distances, the transverse magnetic field components are significantly more non-Gaussian than the radial component. We also find that non-Gaussian behaviour at a given time lag increases with distance but that this can be explained by the corresponding extension of the inertial range to lower frequencies, so that the non-Gaussianity is constant at the integral scale, agreeing with theoretical predictions. We also find that the rate at which non-Gaussian deviations propagate through the cascade decreases slightly with distance.

  2. Interplanetary field enhancements in the solar wind Statistical properties at 0.72 AU

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Arghavani, M. R.; Luhmann, J. G.

    1984-01-01

    A new class of disturbance in the interplanetary magnetic field has been discovered. This disturbance consists of an enhancement in the magnetic field strength lasting tens of minutes to hours. The strength of the enhancement is variable ranging up to over double the background field strength. The peak field pressure can be as high as 10 percent of the solar wind dynamic pressure. These events occur randomly with respect to the position of the spacecraft relative to Venus but not randomly with respect to Venus solar ecliptic longitude. There is a significant tendency for these events to cluster near certain ecliptic longitudes. The field distortion is often greater in the direction perpendicular to the solar wind flow rather than along it. These characteristics suggest that the source of the disturbances are weakly outgassing objects, possibly dispersed along their orbits such as in meteor streams.

  3. Configuration and Evaluation of a Dual-Doppler 3-D Wind Field System

    NASA Technical Reports Server (NTRS)

    Crawford, Winifred C.

    2014-01-01

    Current LSP, GSDO, and SLS space vehicle operations are halted when wind speeds from specific directions exceed defined thresholds and when lightning is a threat. Strong winds and lightning are difficult parameters for the 45th Weather Squadron (45 WS) to forecast, yet are important in the protection of customer vehicle operations and the personnel that conduct them. A display of the low-level horizontal wind field to reveal areas of high winds or convergence would be a valuable tool for forecasters in assessing the timing of high winds, or convection initiation and subsequent lightning occurrence. This is especially important for areas where no weather observation platforms exist. Developing a dual-Doppler radar capability would provide such a display to assist forecasters in predicting high winds and convection initiation. The wind fields can also be used to initialize a local mesoscale numerical weather prediction model to help improve the model forecast winds, convection initiation, and other phenomena. The 45 WS and NWS MLB tasked the Applied Meteorology Unit (AMU) to develop a dual- Doppler wind field display using data from the 45th Space Wing radar, known as the Weather Surveillance Radar (WSR), NWS MLB Weather Surveillance Radar 1988 Doppler (KMLB), and the Orlando International Airport Terminal Doppler Weather Radar (KMCO). They also stipulated that the software used should be freely available. The AMU evaluated two software packages and, with concurrence from NWS MLB and the 45 WS, chose the Warning Decision Support System-Integrated Information (WDSS-II). The AMU collected data from two significant weather cases: a tornadic event on 14 April 2013 and a severe wind and hail event on 12 February 2014. For the 14 April case, the data were from WSR and KMLB. For the 12 February case, the data were from KMCO and KMLB. The AMU installed WDSS-II on a Linux PC, then processed and quality controlled the radar data for display and analysis using WDSS-II tools

  4. Solar Wind Interaction Effects on Mars Crustal Field Measurements Inferred from MHD Simulations

    NASA Astrophysics Data System (ADS)

    Luhmann, Janet G.; Ma, Yingjuan; Brain, David; Lillis, Rob

    2014-05-01

    Analyses of MGS mapping orbit measurements of the planetary magnetic fields of Mars used best practices to minimize the contributions of induced magnetic fields and other features associated with the solar wind interaction. In particular, these concentrated on nightside sampling over long periods of time so as to average out external contributions and perturbations, and eliminated apparently disturbed times in the interplanetary medium. However solar wind interaction-related features at the mapping orbit altitude of 400km may not average out because of non-symmetrical distortions produced by reconnection and dawn-dusk differences associated with the average Parker Spiral external field. The potential issues especially affect the weaker large scale components whose influences are best measured where the solar wind effects are most influential. This includes the important axial dipole field that may be either crustal, a fossil of a previously active dynamo, or evidence of a weak presently active dynamo. We use BATS-R-US models of the Mars-solar wind interaction to investigate these effects and to demonstrate that we still may not know the low order components of the Martian magnetic field very well.

  5. Neutral wind and electric field calculation from monostatic IS radar measurements by means of stochastic inversion

    NASA Astrophysics Data System (ADS)

    Aikio, A.; Nygren, T.; Kuula, R.; Voiculescu, M.

    2012-04-01

    We present the principles of a new method that utilises stochastic inversion in determining the electric field and neutral wind from monostatic beam swing incoherent scatter (IS) radar measurements (Nygren et al., J. Geophys. Res., 2011). The method consists of two stages. In the first inversion of beam-aligned ion velocities from the F region, we get the two perpendicular electric field components and the field-aligned ion velocity profile together with their error estimates. The number of beam directions can be freely selected, as long as there are at least three non-coplanar directions. Typically, we use the best possible time resolution for electric field, which is about 6 min for the Tromso CP2 experiment. In the second stage, the input to the inversion problem consists of beam-aligned ion velocities from the E region as well as the calculated electric field components. The number of applied beam cycles for E-region winds is typically greater than in the first inversion problem, since the neutral wind usually changes more slowly than the electric field. The solution of the second inversion problem gives the most probable values of the three neutral wind components and their errors. In the method described above, a stationary and horizontally homogeneous ionosphere has been assumed. These assumptions are not necessarily valid during a single beam cycle or within the whole measurement region. Disturbances in the receiver may also cause errors. Thus the results may contain errors, which are not of statistical nature. A method has been developed that finds and rejects such measurements from the analysis described above (Nygrén et al., submitted). In consequence, more reliable results for electric fields and neutral winds are expected.

  6. Mapping ERS-1 wind fields over north west Atlantic using a variational objective analysis

    NASA Technical Reports Server (NTRS)

    Siefridt, L.; Legler, D. M.; Barnier, B.; Obrien, J. J.

    1994-01-01

    A variational method is implemented to produce five day mean gridded ERS-1 analyzed wind fields in the north west Atlantic with the aim of providing for wind forcing of basin scale ocean models. The method consists of minimizing a cost functional, designed to measure misfits to prescribed weighted constraints which express a smoothed behavior and the proximity to input data vectors and curl. The weights are empirically determined by comparison with independent ship and buoy data over four five day periods. Root mean square differences between analyzed winds and independent data are thus further decreased: they range from 0.8 up to 1.8 m/s. Some problems present in the initial data remain; they are principally due to incomplete data coverage (instrumental problems), and possibly unresolved ambiguities. The resulting curl fields are smoothed and show coherent patterns. A comparison with the European Center for Medium range Weather Forecasting (ECMWF) analysis is encouraging.

  7. The intrinsic magnetic field and solar-wind interaction of Mars

    NASA Technical Reports Server (NTRS)

    Luhmann, J. G.; Russell, C. T.; Brace, L. H.; Vaisberg, O. L.

    1992-01-01

    The Venus-like interaction between the solar wind and the atmosphere of Mars is examined. The bow shock and magnetosheath of Mars indicate the presence of an obstacle to the solar wind that is somewhat larger than the size of the planet and its observed ionosphere, and also relatively larger than the Venus obstacle under comparable conditions. The intrinsic magnetic field of Mars must be no greater than 1.5 x 10 exp 12 T/cu m, or about 0.0001 times as strong as that of the earth to produce an obstacle of such small size. At least for solar minimum conditions, like those prevailing at the time of the Viking Landers, the ionospheric plasma (thermal) pressure is insufficient to balance the incident solar-wind pressure by itself. The ion and electron temperatures in the Martian ionosphere indicate the presence of local horizontal magnetic fields and heat sources in excess of solar radiation alone.

  8. Wide field-of-view soft X-ray imaging for solar wind-magnetosphere interactions

    NASA Astrophysics Data System (ADS)

    Walsh, B. M.; Collier, M. R.; Kuntz, K. D.; Porter, F. S.; Sibeck, D. G.; Snowden, S. L.; Carter, J. A.; Collado-Vega, Y.; Connor, H. K.; Cravens, T. E.; Read, A. M.; Sembay, S.; Thomas, N. E.

    2016-04-01

    Soft X-ray imagers can be used to study the mesoscale and macroscale density structures that occur whenever and wherever the solar wind encounters neutral atoms at comets, the Moon, and both magnetized and unmagnetized planets. Charge exchange between high charge state solar wind ions and exospheric neutrals results in the isotropic emission of soft X-ray photons with energies from 0.1 to 2.0 keV. At Earth, this process occurs primarily within the magnetosheath and cusps. Through providing a global view, wide field-of-view imaging can determine the significance of the various proposed solar wind-magnetosphere interaction mechanisms by evaluating their global extent and occurrence patterns. A summary of wide field-of-view (several to tens of degrees) soft X-ray imaging is provided including slumped micropore microchannel reflectors, simulated images, and recent flight results.

  9. A non-Gaussian Universal Description of Solar Wind Magnetic Field Fluctuations

    NASA Astrophysics Data System (ADS)

    Zaslavsky, Arnaud; Lion, Sonny; Alexandrova, Olga

    2016-04-01

    The analysis of Probability Distribution Functions (PDF) for velocity and magnetic field fluctuations in solar wind reveals that fluctuations around the mean field occur in clusters and are stronger than expected from Gaussian statistics. This phenomenon is called intermittency and is related to the presence of coherent structures in the solar wind. Here we proposed a universal description of PDF in solar wind using a four-parameter function. We describe the evolution of this parameters with increasing frequencies as well as some implications of this empirical model. Finally we establish the connection with the power spectrum and we discuss possible links between the intermittency, coherent structures and the evolution of the turbulent spectrum at ion scales.

  10. Dependence of Venus ionopause altitude and ionospheric magnetic field on solar wind dynamic pressure

    NASA Technical Reports Server (NTRS)

    Phillips, J. L.; Luhmann, J. G.; Russell, C. T.

    1985-01-01

    The shape of the dayside Venus ionopause, and its dependence on solar wind parameters, is examined using Pioneer Venus Orbiter field and particle data. The ionopause is defined here as the altitude of pressure equality between magnetosheath pressure and ionospheric thermal pressure; its typical altitudes range from about 300 km near the subsolar point to about 900 km near the terminator. A strong correlation between ionopause altitude and magnetosheath magnetic pressure is demonstrated; correlation between magnetic pressure and the normally incident component of solar wind dynamic pressure is also evident. The data support the hypothesis of control of the ionopause altitude by solar wind dynamic pressure, manifested in the sheath as magnetic pressure. The presence of large scale magnetic fields in the ionosphere is observed primarily when dynamic pressure is high and the ionopause is low.